용어집

## 용어집

#rrggbb 라는 형식으로 색상을 표현하는 방법에서 "rr" 은 빨강, "gg" 는 녹색, "bb" 는 파랑이다. 이는 보통 웹 디자인에 많이 사용한다.

  이미지 호스는 여러개의 서로 다른 이미지들을 가진 특별한 붓이다. 예를 들어 발자국 붓은 왼발자국과 오른발자국의 두 가지 이미지를 가지고 있다. 이 가상의 호스 붓을 사용하면 좌우발자국이 번갈아 찍히는 것을 볼 수 있다. 붓의 이러한 애니메이션 기법은 굉장히 유용하다.

A color space is a set of colors which can be displayed or recognized by an input or output device (such as a scanner, monitor, printer, etc.). The colors of a color space are specified as values in a color space system, which is a coordinate system in which the individual colors are described by coordinate values on various axes. Because of the structure of the human eye, there are three axes in color spaces which are intended for human observers. The practical application of that is that colors are specified with three components (with a few exceptions). There are about 30 to 40 color space systems in use. Some important examples are:

  HSV

  CMY(K)

  - YUV

  - YCbCr

  - 디더링(Dithering)

  - Dithering

  - Color

A Parasite is additional data which may be written to an XCF file. A parasite is identified by a name, and can be thought of as an extension to the other information in an XCF file.

  김프 개발자들은 XCF 파일이 다양한 버전에 대해 호환성을 유지하도록 많은 노력을 해왔다. 즉, 김프 2.0 에서 만들어진 파일을 김프 1.2 에서도 읽을 수 있도록 하는 것이다. 하지만 몇몇 정보들은 사용할 수 없을 것이다. 예를 들어 김프 2.0 은 김프 1.2 에 비해 보다 나은 텍스트 관리 방법을 가지고 있는데, 김프 2.0 의 XCF 파일은 이를 텍스트 레이어로 표현하는데, 이를 김프 1.2 에서 읽어들일 경우 그저 일반적인 레이어로 표현할 수밖에 없다.

  YCbCr

  YCbCr

  YCbCr is a color model which was developed for the PAL television standard as a simple modification to the YUV color model. In the meantime, it has become the CCIR-601 standard for image and video recording. For example, it is used for JPEG pictures and MPEG videos, and therefore also on DVDs, video CDs and for most other widespread digital video standards. Note that a color model is still not a color space, since it doesn't determine which colors are actually meant by “red”, “green” and “blue”. For a color space, there must still be a reference to a specific absolute color value.

Alpha Channel

  An alpha channel of a layer is a grayscale image of the same size as the layer representing its transparency. For each pixel the gray level (a value between 0 and 255) represents the pixels's Alpha value. An alpha channel can make areas of the layer to appear partially transparent. That's why the background layer has no alpha channel by default.

  The image alpha channel, which is displayed in the channels dialog, can be considered as the alpha channel of the final layer when all layers have been merged.

  See also 알파 채널의 예제.

Alpha(알파)

  투명도를 참고해라. 알파 채널은 투명도를 조절한다. 몇몇 이미지 포맷들은 단지 하나의 알파 채널만 있어 투명하게 하거나 불투명하게 하거나만 결정할 수 있지만, 다양한 단계의 투명도를 지원하는 포맷도 있다.

  With some image file formats, you can only specify that a pixel is completely transparent or completely opaque. Other file formats allow a variable level of transparency.

An image hose is also sometimes called an “image pipe” or “animated brush”. An image hose is indicated in the Brushes dialog by a small red triangle in the lower right corner of the brush's symbol.

  증가, 페인트 모드(Incremental, paint mode)

  Incremental

  For information concerning creating an image hose, please see the 8절. “GIH 대화 상자” and 7절. “새 붓 추가하기”.

Bézier curve

  A spline is a curve which is defined mathematically and has a set of control points. A Bézier spline is a cubic spline which has four control points, where the first and last control points (knots or anchors) are the endpoints of the curve and the inner two control points (handles) determine the direction of the curve at the endpoints.

  In the non-mathematical sense, a spline is a flexible strip of wood or metal used for drawing curves. Using this type of spline for drawing curves dates back to shipbuilding, where weights were hung on splines to bend them. The outer control points of a Bézier spline are similar to the places where the splines are fastened down and the inner control points are where weights are attached to modify the curve.

  Bézier splines are only one way of mathematically representing curves. They were developed in the 1960s by Pierre Bézier, who worked for Renault.

  Bézier curves are used in GIMP as component parts of Paths.

  The image above shows a Bézier curve. Points P0 and P3 are points on the Path, which are created by clicking with the mouse. Points P1 and P2 are handles, which are automatically created by GIMP when you stretch the line.

BMP

  From The Free Online Dictionary of Computing (13 Mar 01) :

  > bitmap — A data file or structure which corresponds bit for bit with an image displayed on a screen, probably in the same format as it would be stored in the display's video memory or maybe as a device independent bitmap. A bitmap is characterised by the width and height of the image in pixels and the number of bits per pixel which determines the number of shades of grey or colors it can represent. A bitmap representing a colored image (a “pixmap”) will usually have pixels with between one and eight bits for each of the red, green, and blue components, though other color encodings are also used. The green component sometimes has more bits than the other two to cater for the human eye's greater discrimination in this component.

Channel

  Introduction

Channel Mask

  A channel masks is a special type of mask which determines the transparency of a selection. See 마스크는 레이어나 선택과 연동되는 특별한 요소이다. 이를 이용해 레이어나 선택의 투명도를 조절할 수 있다. for a detailed description.

  채널(Channels)

Color

  YUV

  YUV

  The YCbCr model is a slight adaptation of such a brightness-color model. An RGB color value is divided into a basic brightness, Y, and two components, Cb and Cr, where Cb is a measurement of the deviation from gray in the blue direction, or if it is less than 0.5, in the direction of yellow. Cr is the corresponding measurement for the difference in the direction of red or turquoise. This representation uses the peculiarity of the eye of being especially sensitive to green light. That is why most of the information about the proportion of green is in the basic brightness, Y, an only the deviations for the red and blue portions need to be represented. The Y values have twice the resolution of the other two values, Cb and Cr, in most practical applications, such as on DVDs.

Color Depth is simply the number of bits used to represent a color (bits per pixel : bpp). There are 3 channels for a pixel (for Red, Green and Blue). GIMP can supprt 8 bits per channel, referred as eight-bit color. So, GIMP color depth is 8 * 3 = 24, which allows 256 * 256 * 256 = 16,777,216 possible colors (8 bits allow 256 colors).

  Color depth is simply the number of bits used to represent a color (bits per pixel : bpp). There are 3 channels for a pixel (for Red, Green and Blue). GIMP can support 8 bits per channel, referred as eight-bit color. So, GIMP color depth is 8 * 3 = 24, which allows 256 * 256 * 256 = 16,777,216 possible colors (8 bits allow 256 colors).

Dithering

  The exact calculation is more complicated, however, since some aspects of the color perception of the human eye have to be taken into account. For example, green is perceived to be lighter than red, and this is perceived to be lighter than blue. Furthermore, in some systems gamma correction of the basic color is first performed.

  The chrominance signals, and the color difference signals also, contain the color information. They are formed by the difference of blue minus luma or red minus luma.

  U=B-Y

  V=R-Y

  From the three generated components, Y, U and V, the individual color proportions of the basic color can be calculated again later:

  Y + U = Y + ( B - Y ) = Y - Y + B = B

  Y + V = Y + ( R - Y ) = Y - Y + R = R

  Y - B - R = ( R + G + B ) - B - R = G

  Furthermore, because of the structure of the retina of the human eye, it turns out that the brightness information is perceived at a higher resolution than the color, so that many formats based on the YUV color model compress the chrominance to save bandwidth during transmission.

  translator-credits

  Y - B - R = ( R + G + B ) - B - R = G

  Furthermore, because of the structure of the retina of the human eye, it turns out that the brightness information is perceived at a higher resolution than the color, so that many formats based on the YUV color model compress the chrominance to save bandwidth during transmission.

Do not confuse these tiles with those in the Tile Filter

  URI

  URI

  A Uniform Resource Identifier (URI) is a string of characters that serves to identify an abstract or a physical resource. URIs are used for the identification of resources in the Internet (such as web pages, miscellaneous files, calling up web services, and for receivers of e-mail) and they are especially used in the Worldwide Web.

Formats

  Quantization

  Quantization

Formats

  표준 TIFF (Tagged Image File Format) 은 다양한 특성을 가진다. 여섯 개의 인코딩 방법을 지원하며, 각각 검정과 흰색, 그레이스케일, 색상 등 3가지의 이미지 모드를 지원한다. 비압축 TIFF 이미지는 픽셀당 1, 4, 8, 24 비트를 사용할 수 있다. 이는 굉장히 높은 화질의 파일 포맷으로 FrameMaker 이나 CorelDRAW 등의 다른 프로그램으로 보내는데 아주 좋다.

Gamma is used as an exponent (power) in the correction equation. Gamma compression (where gamma < 1) is used to encode linear luminance or RGB values into color signals or digital file values, and gamma expansion (where gamma > 1) is the decoding process, and usually occurs where the current-to-voltage function for a CRT is non-linear.

  In GIMP, gamma is an option used in the brush tab of the GIMPressionist filter and in the Flame filter. The display filters also include a Gamma filter. Also see the Levels Tool, where you can use the middle slider to change the gamma value.

  Gamut

  Gamut

  In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced /ˈgæmət/), is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a certain output device. Another sense, less frequently used but not less correct, refers to the complete set of colors found within an image at a given time. In this context, digitizing a photograph, converting a digitized image to a different color space, or outputting it to a given medium using a certain output device generally alters its gamut, in the sense that some of the colors in the original are lost in the process. [위키백과 - 개멋(Gamut)]

GIF

  CompuServe 사의 대표적인 작품이며, Unisys 사의 LZW 압축기법을 사용한다. GIF 이미지는 8 비트의 인덱스 색상과 이진 투명도를 지원한다(반투명은 지원하지 못한다). 그리고 몇몇 프로그램에서 인터레이스 로딩을 할 수 있다. 또 GIF 포맷은 애니메이션과 코멘트를 지원한다. 이 때문에 투명한 웹그래픽스나 GIF 애니메이션 등으로 많이 쓰이는 포맷이다. 현재는 PNG 포맷으로 대체되고 있다.

GIF was introduced by CompuServe in 1987. It became popular mostly because of its efficient, LZW compression. The size of the image files required clearly less disk space than other usual graphics formats of the time, such as PCX or MacPaint. Even large images could be transmitted in a reasonable time, even with slow modems. In addition, the open licensing policy of CompuServe made it possible for any programmer to implement the GIF format for his own applications free of charge, as long as the CompuServe copyright notice was attached to them.

  One color entry in the palette can be defined to be transparent. With transparency, the GIF image can look like it is non-rectangular in shape. However, semi-transparency, as in PNG, is not possible. A pixel can only be either entirely visible or completely transparent.

  The first version of GIF was 87a. In 1989, CompuServe published an expanded version, called 89a. Among other things, this made it possible to save several images in one GIF file, which is especially used for simple animation. The version number can be distinguished from the first six bytes of a GIF file. Interpreted as ASCII symbols, they are “GIF87a” or “GIF89a”.

  GNU

  GNU는 GNU's Not Unix 의 약자로, 자유 운영체제 프로젝트이다. 이 프로젝트는 1983년에 자유 소프트웨어에 대한 제작과 지원을 하는 기관인 Free Software Fundation 에서 시작되었다. 김프는 공식적인 GNU 응용 프로그램이다. 더 자세한 내용은 위키피아에서 확인할 수 있다.

  The name came about from the naming conventions which were in practice at MIT, where Stallman worked at the time. For programs which were similar to other programs, recursive acronyms were chosen as names. Since the new system was to be based on the widespread operating system, Unix, Stallman looked for that kind of name and came up with GNU, which stands for “GNU is not Unix”. In order to avoid confusion, the name should be pronounced with the “G”, not like “new”. There were several reasons for making GNU Unix-compatible. For one thing, Stallman was convinced that most companies would refuse a completely new operating system, if the programs they used wouldn't run on it. In addition, the architecture of Unix made quick, easy and distributed development possible, since Unix consists of many small programs that can be developed independently of each other, for the most part. Also, many parts of a Unix system were freely available to anyone and could therefore be directly integrated into GNU, for example, the typesetting system, TeX, or the X Window System. The missing parts were newly written from the ground up.

GIMP (GNU Image Manipulation Program) is an official GNU application [위키백과 - GNU].

  Grayscale

  Grayscale

  Overview

Grayscale is a mode for encoding the colors of an image which contains only black, white and shades of gray.

  Grayscale image files (8-bit) are smaller than RGB files.

  When you create a new image, you can choose to create it in Grayscale mode (which you can colorize later, by changing it to RGB mode). You can also change an existing image to grayscale by using the Grayscale, Desaturate, Decompose, Channel Mixer, although not all formats will accept these changes. Although you can create images in Grayscale mode and convert images to it, it is not a color model, in the true sense of the word.

  Guides

  Using

HSV

  The RGB mode is very well suited to computer screens, but it doesn't let us describe what we see in everyday life; a light green, a pale pink, a dazzling red, etc. The HSV model takes these characteristics into account. HSV and RGB are not completely independent of each other. You can see that with the Color Picker tool; when you change a color in one of the color models, the other one also changes. Brave souls can read Grokking the GIMP, which explains their interrelationship.

In GIMP, you can feather the edges of a selection. Brushes can also have feathered edges.

  The process of Feathering makes a smooth transition between a region and the background by softly blending the edges of the region.

  파일포맷은 이미지를 작성하는 방법이다. 따라서 상황에 맞게 적절한 포맷을 선택해 주어야 한다. 파일 포맷의 예로 JPEG이나 PostScript가 있다.

Indexed colors

  이미지를 크게 할때, 이미지의 해상도가 충분치 않으면 픽셀들이 벌어지게 된다. 이때 생기는 공간을 주변 픽셀에 근거하여 채우는 것이 보간이다. 김프에서 보간법은 속도로 표시된다. 빠른 방법은 낮은 품질의 변환이고, 느린 방법은 높은 품질의 변환이다.

  None (sometimes called “Nearest Neighbor”): The color of each pixel is copied from its closest neighboring pixel in the original image. This often results in aliasing (the “stair-step” effect) and a coarse image, but it is the fastest method.

L*a*b*

  The Lab color space (also called the L*a*b* color space) is a color model developed in the beginning of the 1930s by the Commission Internationale d`Eclairage (CIE). It includes all the colors that the human eye can perceive. That contains the colors of the RGB and the CMYK color spaces, among others. In Lab, a color is indicated by three values: L, a and b. Here, the L stands for the luminance component — corresponding to the gray value — and a and b represent the red-green and blue-yellow parts of the color, respectively.

  레이어는 쌓여있는 판자나 입고 있는 옷을 생각해보면 된다. 입고 있는 옷의 각 부분은 레이어 대화 상자 에 있는 각 레이어와 같다. 그리고 레이어는 각각 다른 것들의 위에 쌓여져 있다. 제일 아래의 레이어는 이미지의 배경으로 이미지의 다른 성분들이 그 위에 놓여지게 된다.

Linear (sometimes called “Bilinear”): The color of each pixel is computed as the average color of the four closest pixels in the original image. This gives a satisfactory result for most images and is a good compromise between speed and quality.

  Interpolation means calculating intermediate values. When you enlarge (“digitally zoom”) or otherwise transform (rotate, shear or give perspective to) a digital image, interpolation procedures are used to compute the colors of the pixels in the transformed image. GIMP offers three interpolation methods, which differ in quality and speed. In general, the better the quality, the more time the interpolation takes (see Interpolation methods).

  GIMP uses interpolation when you Scale an image, Scale a layer, and when you Transform an image.

Moiré Effect

  The moiré effect (pronounce “Moa-ray”) is an unintended pattern which appears when a regular pattern of grids or lines interferes with another regular pattern placed over it. This can happen, for example, when you are scanning an image with a periodic structure (such as a checkered shirt or a half-toned image), scanning a digital image, taking a digital photograph of a periodic pattern, or even when silkscreening.

  XCF

  .xcf

One way to reduce quantization effects is to use Dithering. The operations in GIMP which perform dithering are the Blend tool (if you have enabled the dithering option) and the Convert to Indexed command. However, they only work on RGB images and not on Indexed images.

  Color Management

  Rendering intents are ways of dealing with colors that are out-of- GIF colors present in the source space that the destination space is incapable of producing. There are four rendering intents defined by the ICC:

Optional extensions for the GIMP. Plugins are external programs that run under the control of the main GIMP application and provide specific functions on-demand. See 1절. “플러그인” for further information.

  .png

PDB

  All of the functions which GIMP and its extensions make available are registered in the Procedure Database (PDB). Developers can look up useful programming information about these functions in the PDB by using the Procedure Browser.

  PDF

PDF

  Formats

PDF 포맷은 포스트스크립트(Postscript)의 부족한 부분을 채우기 위해 어도비(Adobe) 사에 의해 개발되었다. PDF 파일은 포스트스크립트 파일보다 상당히 작다. 김프에서는 고스트스크립트(Ghostscript)를 통해 포스트스트립트와 함께 PDF 포맷을 지원한다.

  A pixel is a single dot, or “picture element”, of an image. A rectangular image may be composed of thousands of pixels, each representing the color of the image at a given location. The value of a pixel typically consists of several Channels, such as the Red, Green and Blue components of its color, and sometimes its Alpha (transparency).

Perceptual

  Relative colorimetric

  This rendering intent is typically used for spot colors. Colors that are not out of gamut are left unchanged. Colors outside the gamut are converted to colors with the same lightness, but different saturation, at the edge of the gamut.

    Saturation

  This method is typically used for business graphics. The relative saturation of colors is mostly maintained, but lightning is usually changed.

    Absolute colorimetric

  This rendering intent is most often used in proofing. It preserves the native device white point of the source image.

    RGB

  RGB

    Color

Plugin

  Definition

Saturation

  Color

Since URLs are the first and most common kinds of URIs, the terms are often used synonymously.

  Value

  Color

Some typical file formats for saving images are JPEG, TIFF, PNG and GIF. The best file format for saving an image depends upon how the image is intended to be used. For example, if the image is intended for the internet, file size is a very important factor, and if the image is intended to be printed, high resolution and quality have greater significance. See Format types.

  Selection

  Floating selection

Subtractive color synthesis

  Subtractive color model

  GIMP does not currently support the CMYK model. (An experimental plug-in providing rudimentary CMYK support can be found [PLUGIN-SEPARATE].)

  This is the mode used in printing. These are the colors in the ink cartridges in your printer. It is the mode used in painting and in all the objects around us, where light is reflected, not emmitted. Objects absorb part of the light waves and we see only the reflected part. Note that the cones in our eyes see this reflected light in RGB mode. An object appears Red because Green and Blue have been absorbed. Since the combination of Green and Blue is Cyan, Cyan is absorbed when you add Red. Conversely, if you add Cyan, its complementary color, Red, is absorbed. This system is subtractive. If you add Yellow, you decrease Blue, and if you add Magenta, you decrease Green.

  그림 1059. It would be logical to think that by mixing Cyan, Magenta and Yellow, you would subtract Red, Green and Blue, and the eye would see no light at all, that is, Black. But the question is more complex. In fact, you would see a dark brown. That is why this mode also has a Black value, and why your printer has a Black cartridge. It is less expensive that way. The printer doesn't have to mix the other three colors to create an imperfect Black, it just has to add Black.

  Color depth

  Color depth

  bpp

SVG stands for Scalable Vector Graphics. It a format for two-dimensional vector graphics, both static and animated. You can export GIMP paths to SVG and you can import SVG documents into GIMP from a vector graphic software. See [위키백과 - SVG] for more details.

  SVG stands for Scalable Vector Graphics. It is a format for two-dimensional vector graphics, both static and animated. You can export GIMP paths to SVG and you can import SVG documents into GIMP from a vector graphic software. See [위키백과 - SVG] for more details.

The basic operations provided by the clipboard are “Cut”, “Copy”, and “Paste”. Cut means that the item is removed from the document and copied to the clipboard. Copy leaves the item in the document and copies it to the clipboard. Paste copies the contents of the clipboard to the document. The GIMP makes an intelligent decision about what to paste depending upon the target. If the target is a canvas, the Paste operation uses the image clipboard. If the target is a text entry box, the paste operation uses the text clipboard.

  CMY, CMYK

  CMYK

  Color

The quality of the result depends on the number of samples. Supersampling is often performed at a range of 2× to 16× the original size. It greatly increases the amount of time needed to draw the image and also the amount of space needed to store the image in memory.

  SVG

  SVG

  Formats

This rendering intent is most often used in proofing. It preserves the native device white point of the source image.

  이 기술은 김프로 하여금 보간법보다 더 많은 주변의 픽셀들을 가지고 변할 색을 계산하는 것이다. 화질은 좋아지는 대신 조금 더 많은 시간을 필요로 한다.

This term often refers to the light intensity, the luminosity of a color. It varies from 0 (black) to 100 (full light).

  .xcf

Tile

  At any time, a tile may be in main memory, in the tile cache in RAM, or on disk. Tiles which are currently being worked on are in main memory. Tiles which have been used recently are in RAM. When the tile cache in RAM is full, tiles which have been used least recently are written to disk. GIMP can retrieve the tiles from RAM or disk when they are needed.

URL

  Uniform Resource Locator: 월드와이드웹(World Wide Web)에서 주소를 표시하는 방식이다.

Use JPEG to create web graphics or if you don't want your image to take up a lot of space. JPEG is a good format for photographs and for computer-generated images (CGI). It is not well suited for:

  Black and white images (only black and white, one bit per pixel) or

  half-toned images (newsprint).

  - Other formats, such as GIF, PNG or JBIG, are far better for these kinds of images.

  - In general, JPEG transformations are not reversible. Opening and then saving a JPEG file causes a new, lossy compression. Increasing the quality factor later will not bring back the image information which was lost.

  - L*a*b

  The Lab color space (also called the L*a*b color space) is a color model developed in the beginning of the 1930s by the Commission Internationale d`Eclairage (CIE). It includes all the colors that the human eye can perceive. That contains the colors of the RGB and the CMYK color spaces, among others. In Lab, a color is indicated by three values: L, a and b. Here, the L stands for the luminance component — corresponding to the gray value — and a and b represent the red-green and blue-yellow parts of the color, respectively.

  In contrast to RGB or CMYK, Lab is not dependent upon the various input and output devices. For that reason, it is used as an exchange format between devices. Lab is also the internal color model of PostScript Level II.

When you convert an image to Indexed mode, you can choose between two variants of Floyd-Steinberg dithering.

  Gamma

  Gamma or gamma correction is a non-linear operation which is used to encode and decode luminance or color values in video or still image systems. It is used in many types of imaging systems to straighten out a curved signal-to-light or intensity-to-signal response. For example, the light emitted by a CRT is not linear with regard to its input voltage, and the voltage from an electric camera is not linear with regard to the intensity (power) of the light in the scene. Gamma encoding helps to map the data into a perceptually linear domain, so that the limited signal range (the limited number of bits in each RGB signal) is better optimized perceptually.

YCbCr

  Saturation : This value describes how pale the color is. A completely unsaturated color is a shade of gray. As the saturation increases, the color becomes a pastel shade. A completely saturated color is pure. Saturation values go from 0 to 100, from white to the purest color.

  Value : This value describes the luminosity, the luminous intensity. It is the amount of light emitted by a color. You can see a change of luminosity when a colored object is moved from being in the shadow to being in the sun, or when you increase the luminosity of your screen. Values go from 0 to 100. Pixel values in the three channels are also luminosities: “Value” in the HSV color model is the maximum of these elementary values in the RGB space (scaled to 0-100).

  Brief description of the HSV components:

  Hue

    This is the color itself, which results from the combination of primary colors. All shades (except for the gray levels) are represented in a chromatic circle: yellow, blue, and also purple, orange, etc. The chromatic circle (or “color wheel”) values range between 0° and 360°. (The term “color” is often used instead of “Hue”. The RGB colors are “primary colors”.)

  This rendering intent is most often used in proofing. It preserves the native device white point of the source image.

    This value describes how pale the color is. A completely unsaturated color is a shade of gray. As the saturation increases, the color becomes a pastel shade. A completely saturated color is pure. Saturation values go from 0 to 100, from white to the purest color.

  This term often refers to the light intensity, the luminosity of a color. It varies from 0 (black) to 100 (full light).

    This value describes the luminosity, the luminous intensity. It is the amount of light emitted by a color. You can see a change of luminosity when a colored object is moved from being in the shadow to being in the sun, or when you increase the luminosity of your screen. Values go from 0 to 100. Pixel values in the three channels are also luminosities: “Value” in the HSV color model is the maximum of these elementary values in the RGB space (scaled to 0-100).

YUV

  그림 1061. GIMP uses eight bits per channel for each primary color. That means there are 256 intensities (Values) available, resulting in 256×256×256 = 16,777,216 colors.

  It is easy to see that no light (0R+0G+0B) produces complete darkness, black, and that full light (255R+255G+255B) produces white. Equal intensity on all color channels produces a level of gray. That is why there can only be 256 gray levels in GIMP.

  Mixing two Primary colors in RGB mode gives a Secondary color, that is, a color in the CMY model. Thus combining Red and Green gives Yellow, Green and Blue give Cyan, Blue and Red give Magenta. Don't confuse secondary colors with Complementary colors which are directly opposite a primary color in the chromatic circle:

  Colorcircle

  Mixing a primary color with its complementary color gives gray (a neutral color).

  It is important to know what happens when you are dealing with colors in GIMP. The most important rule to remember is that decreasing the intensity of a primary color results in increasing the intensity of the complementary color (and vice versa). This is because when you decrease the value of a channel, for instance Green, you automatically increase the relative importance of the other two, here Red and Blue. The combination of these two channels gives the secondary color, Magenta, which is the complementary color of Green.

  그림 1062. Exercise : You can check this out. Create a new image with only a white background (255R+255G+255B). Open the Tools → Color Tools → Levels dialog and select the Red channel. If necessary, check the preview box. Move the white slider to the left to decrease the Red value. You will notice that the background of your image gets closer and closer to Cyan. Now, decrease the Blue channel: only the Green will remain. For practice, go backwards, add a color and try to guess what hue will appear.

  The Color Picker tool lets you find out the RGB values of a pixel and the hextriplet for the color.

  표본 합치기(Sample Merge)

  Saturation

각 이미지는 각각의 채널로 분리된다음 출력장치로 보내지기 전에 다시 합쳐진다. 이 출력장치는 대부분 모니터인데, 여기서는 이미지를 빨강, 녹색, 파랑으로 나눠 모니터에 표현하는데 쓰인다. 물론 다른 출력 장치에서는 다른 채널을 사용할 수도 있다.

  Channels can be useful when you are working on an image which needs adjustment in one particular color. For example, if you want to remove “red eye” from a photograph, you might work on the Red channel.

  You can look at channels as masks which allow or restrict the output of the color that the channel represents. By using Filters on the channel information, you can create many varied and subtle effects on an image. A simple example of using a Filter on the color channels is the Channel Mixer filter.

  In addition to these channels, GIMP also allows you to create other channels (or more correctly, Channel Masks), which are displayed in the lower part of the Channels dialog. You can convert a selection to a channel mask by using the Save to Channel command. You can also create a channel by right-clicking in the Channels dialog and using the New channel command. See the glossary entry on Masks for more information about Channel Masks.

  클립보드(Clipboard)

  클립보드는 응용 프로그램이나 문서 사이에 전송되는데 사용되는 메모리의 임시 공간을 가리킨다. 김프에서는 다른 운영체제에서 사용하는 클립보드와 다소 다른 클립보드를 사용한다. Linux/XFree 에서는 XFree 의 클립보드는 텍스트를 저장하고, 김프 내부의 이미지 클립보드는 이미지 문서사이에 사용되는 이미지를 저장한다. 김프가 운영체제의 클립보드를 사용한다면 그 차이는 명백하게 드러날 것이다. 이 차이점들은 김프의 각 패키지에 따른 특수한 문서에서 볼 수 있다.

  대부분의 기본 작업들은 클립보드로 잘라내기, 복사하기, 붙여넣기 등을 사용할 수 있다. 잘라내기는 아이템을 클립보드로 보낸 후 삭제할 때 쓰이고 복사하기는 문서에 아이템을 남긴채 클립보드로 복사한다. 붙여넣기는 클립보드에 무엇이 있던간에 문서로 복사한다. 여기서 김프는 해당 문서에 어떤 것을 붙여넣을지 지능적으로 결정을 하게 된다. 타겟이 캔버스라면, 붙여넣기 작업은 이미지 클립보드를 사용하고, 텍스트 박스라면 텍스트 클립보드를 사용한다.

경로(Path)

  경로 는 다각형이나, 곡선 등 1차원의 흔적이다. 김프에서 경로의 주 용도는 선택의 외각을 만들거나, 테두리를 그려 곡선을 만드는 것이다. 경로에 대한 기본 정보는 경로 섹션을 참고하면 되고, 경로를 만들고 편집하는 방법에 대해서는 경로 도구 섹션을 참고하면 된다.

  See the Paths Concepts and Using Paths sections for basic information on paths, and the Path Tool section for information on how to create and edit paths. You can manage the paths in your image with the Paths dialog.

디더링은 수학적인 방법으로 적은 색상을 가진 이미지를 좀더 풍부한 색상을 가진 이미지처럼 표현하는 것이다. 디더링은 출력 장치에 의존하는 방법들과 다른 방법으로 이를 표현한다. 특히 효과적인 방법 중 하나는 다른 색상들을 섞어서 또다른 색상을 만들어내는 것이다. 이것은 인간의 눈과 복잡한 색상 무늬를 볼때 일어나는 착시등에 근거한 것이다. 일반적인 디더링 효과는 텔레비전이나 신문을 볼때 일어난다. 이미지를 보는 거리로 인해 많은 색상들이나 그림자가 생긴다. 하지만 정확히 예는 아니다. 텔레비젼의 색상은 단지 세가지 색상만의 조합으로 표현되는 것이다. 그리고 흑백 신문은 단지 검정 잉크만을 사용한다. 그리고 신문의 그림은 회색톤으로 표현된다. 디더링에는 이보다 훨씬 더 큰 효과를 가지는 많은 기술들이 있다.

  Also note that although GIMP itself uses 24-bit colors, your system may not actually be able to display that many colors. If it doesn't, then the software in between GIMP and your system may also dither colors while displaying them.

  See also the glossary entry on Floyd-Steinberg dithering, which is used in GIMP.

  EXIF

  EXIF

  Exchangeable image file format (official abbreviation Exif, not EXIF) is a specification for the image file format used by digital cameras. It was created by the Japan Electronic Industry Development Association (JEIDA). The specification uses the existing JPEG, TIFF Rev. 6.0, and RIFF WAVE file formats, with the addition of specific metadata tags. It is not supported in JPEG 2000 or PNG. Version 2.1 of the specification is dated June 12, 1998 and version 2.2 is dated April 2002. The Exif tag structure is taken from that of TIFF files. There is a large overlap between the tags defined in the TIFF, Exif, TIFF/EP and DCF standards [위키백과 - EXIF 데이터].

떠있는 선택은 고정되기 전까지 이미지의 어떤 레이어에서도 다른 작업을 할 수 없도록 된 레이어와 비슷하다. 선택이 떠있는 동안은 어떤 작업도 그 선택이 있는 이미지를 변경할 수 없다.

  A floating selection (sometimes called a “floating layer”) is a type of temporary layer which is similar in function to a normal layer, except that a floating selection must be anchored before you can resume working on any other layers in the image.

  In early versions of GIMP, when GIMP did not use layers, floating selections were used for performing operations on a limited part of an image (you can do that more easily now with layers). Now floating selections have no practical use, but you must know what you have to do with them.

마스크(Masks)

  Masks

마스크는 레이어나 선택과 연동되는 특별한 요소이다. 이를 이용해 레이어나 선택의 투명도를 조절할 수 있다.

  선택 마스크 라 불리우는 채널 마스크: 이는 이미지의 알파 채널로 구현된다. 마스크를 제거하거나 선택을 확장시키려면 흰색으로 칠하면 되고, 선택을 축소시키려면 검정색으로 칠하면 된다. 이를 통해 선택을 정확하게 잘라낼 수도 있다. 또한 채널 메뉴 의 "알파를 선택으로" 를 이용하면 선택을 저장했다가 나중에 불러 올 수도 있다. 김프에서 채널 마스크는 특별한 형태인 퀵 마스크 를 구현하는 중요한 부분이다. 더 자세한 내용은 선택 마스크 를 보면 된다.

  Moiré Effect

  - Layer Mask: Every layer can have its own mask. The layer mask represents the Alpha channel of the layer and allows you to manage its transparency. By painting on the layer mask, you can make parts of the layer opaque or transparent: painting with black makes the layer transparent, painting with white makes the layer opaque and painting with shades of gray makes the layer semi-transparent. You can use all paint tools to paint on the mask. You can also apply a filter or copy-paste. You can use the Layer mask for transition effects, volume effects, merging elements from another image, etc. See the Layer Mask section for more details.

  - The moiré effect (pronounce “Moa-ray”)is an unintended pattern which appears when a regular pattern of grids or lines interferes with another regular pattern placed over it. This can happen, for example, when you are scanning an image with a periodic structure (such as a checkered shirt or a half-toned image), scanning a digital image, taking a digital photograph of a periodic pattern, or even when silkscreening.

마이크로소프트사의 윈도우즈에서 사용되는 비압축 비트맵 포맷이다. 보통 1, 4, 혹은 8비트의 색상을 사용한다.

  Bump mapping is only one (very effective) way of simulating surface irregularities which are not actually contained in the geometry of the model.

안내선을 사용하려면 눈금자에 마우스 포인터를 두고 좌버튼 클릭을 한 후에 이미지로 드래그하면 안내선이 나타나 포인터를 따라간다. 안내선은 수평 안내선과 수직 안내선이 있으며, 이들은 인쇄되지 않는다.

  위치시키는 것을 쉽게 하기 위해서 안내선에 맞추기 옵션을 통해 안내선에 '자성을 띄게' 할 수도 있다.

  For more information see 2.2절. “안내선”.

안티알리아싱(Antialiasing)

  안티알리아싱은 알리아싱의 반대 작업으로, 배경과 그림 사이의 경계를 부드럽게 처리하는 것이다. 일반적으로 픽셀의 농도나 불투명도가 변경되어 배경과 부드럽게 합쳐지게 된다. 선택의 경우에는 선택의 경계에 영향을 주어 경계의 불투명도가 낮아진다.

어도비(Adobe) 사에 의해 개발된 포스트스크립트(PostScript)는 프린터 등 여러 출력장치에 널리 사용된 페이지 표현 언어이다. 이것은 문서들을 배치하는데 좋은 방법이다. 하지만 김프에서는 이를 직접 지원하지 않고 포스트스크립트를 지원하는 강력한 자유 프로그램인 고스트스크립트(Ghostscript)를 통해 간접 지원한다.

  고스트스크립트(Ghostscript) 프로젝트 페이지 소스사이트 [GHOSTSCRIPT] 를 방문한다.

  gnu-gs 혹은 ghostscript(비상업용) 패키지를 찾아 다운로드한다.

위의 두 이미지는 60 크기의 붓으로 그린 것들이다. 왼쪽 그림은 미증가 페인팅이고, 오른쪽 그림은 증가 페인팅이다. 각 붓의 증가 페인트 모드 결과는 스트로크의 지속시간 동안 그 전의 붓 모양에 추가되는 것된 모양으로 표현된다.

  Incremental mode is a tool option that is shared by several brush tools, except those which have a “rate” control, which automatically implies an incremental effect. You can set it by checking the Incremental checkbox in the toolbox for the tool (Paintbrush, Pencil and Eraser).

  Indexed Colors

  The two images above were created using a brush with spacing set to 60 percent. The image on the left shows non-incremental painting and the image on the right shows the difference with incremental painting.

  Incremental mode is a tool option that is shared by several brush tools, except those which have a “rate” control, which automatically implies an incremental effect. You can set it by checking the Incremental checkbox in the tool option dialog for the tool (Paintbrush, Pencil and Eraser).

이 포맷은 GIF 포맷 의 대안으로 제시된 것이다. 따라서 GIF의 상표권과 특허권에 대한 대책을 가지고 있다. 그리고 인덱스 색상, 그레이스케일, 트루컬러 이미지 등을 지원하며, 알파채널도 지원한다. PNG 역시 압축기법을 사용하지만 JPEG 과는 달리 정보 손실이 없다.

  PostScript

이미지의 레이어 모습 :

  The final image:

  행진하는 개미(Marching Ants)

  그림 1060. Example image with layers

  Representation of an image with layers

  The final image

페더링(Feathering)

  페더링은 영역의 경계 부분을 배경화면과 섞어 부드럽게 만들어주는 작업이다.

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