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# Profile Checker Help Window

LProf is an open source application that creates ICC profile for cameras, scanners and monitors.

#### Profile Checker

The profile checker is a tool for inspecting some of the profile internal data. It allows users to inspect a number of different aspects of the profile. In most cases users will be checking the profiles accuracy. Feel free to experiment, the profile checker will never write to or modify your profile, so you can play with it in a safe way.

When the Profile Checker button is selected on the main LPROF dialog information about the last profile created is passed to the Profile Checker dialog. The user can over ride these values to look at other profiles but in most cases the default data passed to the Profile Checker is exactly what is wanted. To start the inspection process press the "Inspect Profile" button.

#### Info Tab

The info tab contains basic information about the profile. This includes:

1. Identification information entered in the "Profile Identification" dialog.

2. The profile white point.

3. The profile media white point.

4. The profile primaries.

5. The profile red, green and blue gamma.

6. The target reference file name.

7. The measurement sheet file name.

#### CIE Diagram Tab

This tab contains a CIE or chromaticity diagram. A CIE diagram is a representation of all of the colors that a person with normal vision can see. This is represented by the colored sail shaped area. In addition, you will see a triangle that is superimposed on the diagram outlined in white. This triangle represents that outer boundaries of the color space of the device that is characterized by the profile being inspected. This is called the device gamut. The corners of the triangle are known as the device primaries. For devices with very large gamuts one or more of the primaries will actually be outside of the visible spectrum (IE. out side the sail shaped colored area). This ca happen with wide gamut devices like cameras and some times film scanners.

In addition there are black dots and yellow lines on the diagram. Each black dot represents one of the measurement points that was used to create this profile. The yellow line represents the amount that each point is corrected by the profile and the direction of the correction. The length of the yellow lines give an indication of how much the various colors are being adjusted by the profile.

#### ΔE Report Tab

ΔE (pronounced delta E) is a standard way to measure color errors. On the "ΔE report tab" you will see the error statistics. (unless you forgot to set the profile verbosity to "Verbose, store anything" in the Profile Parameters dialog). This report gives an indication how close the colors will be once the profile is applied to the image. A ΔE of 1.0 is right at the threshold of human perception. That is under perfect lighting conditions, sun light for example, when comparing two color patches that are different by 1.0 ΔE just over half of those looking that those patches side by side will correctly identify them as not being the exact same color. Think of it as the colormeteric equivalent of a decibel. It is fairly typical to get an average ΔE in the range 0.5 to 3.0 and maximum ΔE in the range of 3.0 to 8.0 for camera/scanner profiles created with LProf. For IT8.7 images that are RAW scans that are produced by some scanners or some scanner software you can expect higher ΔE numbers.

These numbers are not critical and are more of an indication of how good of a fit the regression algorithm in LProf was able to obtain with the data points from the target and still produce smooth tone curves. These numbers are influenced by the quality and age of the IT8 target and the quality of the measurements in the targets reference file as well as other factors. Hand measured targets will usually give lower ΔE numbers than the same target using batch average measurements if all else is equal (target age, scanner settings...). Of course hand measured targets are significantly more expensive than targets that only have batch average measurements in the reference file.

#### FIXME

#### Correction Combo Documentation Goes Here

#### Curves Tab

The curves tab shows the correction curves applied to each color channel by the profile. When the device being profiled has good color balance the red, green and blue curves will lay on top of each other. But if the color balance of the device is off significantly the curves will separate from each other. Also as the gamma of the devices response changes the amount of curvature in these correction curves will change. You can use the Intent drop down list in the upper right hand part of the dialog to display different curves for each intent type.

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Copyright © 2006 LProf | Trademarks | LPROF 1.11.5