Color Lists

From ColorWiki

Go to the previous section: The Grapher

Color Lists are produced when profiles are built using profile construction software. You can also produce them synthetically in a text editor or spreadsheet program. Typically device settings (RGB, CMYK, and so forth) are compared with CIE color readings (XYZ, Lab, etc) to create an ICC profile. In most profiling applications, these color lists can be exported and brought into use within ColorThink.

Color Lists can be used to:

• Track device behavior.
• Compare color measuring instruments, media, inks, output devices and so forth.
• Evaluate profile integrity

Contents 1 How Color Lists are Specified 2 An example of a Color List 3 To Open a Color List 4 To Apply a Profile to a Color List 5 To Change Rendering Intents 6 To Change the CIE Color Units 7 To Add Colors to a color list 8 To Graph the Color List

How Color Lists are Specified

Color Lists are specified either by CIE color or device color. This is an important differentiation when applying a profile to a color list. If a list is defined by CIE color, then the “Colors” column values will not change. Any device profile can be applied to the list and the device colorspace will reflect the device colorspace of the applied profile. If a list is defined by device color, then only device profiles whose device color spaces match the device space of the list may be applied to the list. Either the Color or Device column text will be marked in bold text showing how the list is specified.

When adding a color to an empty color list, the color’s type will determine how all colors in the list are specified. For example, if a color is dragged from a list in which all colors are specified by CIE color (rather than device color), then the new list will be marked as specified by CIE color

Data files from profiling packages or color measurement readings are opened into a color list and the data format of the files determines how the colors in the list are specified.

Data files from the following programs are supported:

• Color Savvy
• ColorBlind
• GretagMacbeth (ISO standard) (spectral measurements not supported yet)
• Heidelberg/Linocolor
• Kodak
• Monaco
• Praxisoft (raw Lab values)
• Spectrocam

Please send additional file types to CHROMiX for inclusion in future versions of ColorThink.

To create a custom data file by hand in a text editor or Excel, copy one of the files supplied with the tutorials and modify its contents, retaining the file formatting.

An example of a Color List

ColorThink recognizes color lists that correspond to the CGATS format as well as several other common industry formats.

A simple color list can be easily created with a worksheet program (such as Excel) or using an ordinary text editor. This is essentially a text document with a few code words at the beginning and end, with your list of Lab values in-between.

Below is an example using Lab values. Note that:

• All fields should be tab-delimited.
• The header needs to have data format information.

BEGIN_DATA_FORMAT
Lab_L Lab_a Lab_b
END_DATA_FORMAT
BEGIN_DATA
91 -2 96
44 -29 2
END_DATA

Don't forget to include "END_DATA" on the last line. Feel free to copy and paste the code above and use it as a template for your data.

To Open a Color List

• Select “File:Open” and choose a text-based color list or
• Drag a color list onto the menu bar or
• Export a list of colors from the Image Inspector or
• Export a list of colors from a Named Color Profile (NCP) in the Profile Inspector
• Select “Color:New Color List...” to open a new empty color list .

To Apply a Profile to a Color List

• Drag a profile icon from anywhere in ColorThink or directly from the Finder onto the Color List window or
• Pull down the profile tab and choose the profile from the Add: menu.

ColorThink will apply the profile to the list converting from CIE colors (Lab, XYZ, Yxy, and so forth) to device colors (RGB, CMYK, etc) or vice versa. If the color list has been defined with a device colorspace that does not match the profile’s device colorspace, the conversion will not take place.

To Change Rendering Intents

• Pull down the profile tab
• Choose the desired rendering intent
• Close the profile tab

ColorThink will recalculate the colors according to the new settings

To Change the CIE Color Units

• Select the desired units from the “Color” popup menu at the top of the CIE color column. Lab, Luv, LCH, XYZ, and Yxy units are available.

To Add Colors to a color list

• Drag a color tab from the Profile Inspector or another color list

When adding a color to an empty color list, the color’s type will determine how all colors in the list are specified. For example, if a color is dragged from a list in which all colors are specified by CIE color (rather than device color), then the new list will be marked as specified by CIE color. Please see “How Color Lists are Specified” for more information.

To Graph the Color List

• Click the 2D or 3D Grapher button to create a new graph or
• Drag the list icon onto an existing graph to add the list
• Drag a single color onto the 2D or 3D buttons in the Menu Bar to graph it.

If the color list is specified only using device colors, there will be no CIE colors to graph and the 2D and 3D Grapher buttons will be disabled. Apply a profile to the list as described above and then graph the resulting CIE color data.

Color lists can also be saved. When saving a color list, you may specify which data will be saved. This includes Lab, XYZ (when CIE color information is available) and device colors (RGB, CMYK, etc when device data is available). The current format supported is the CGATS format used for IT8 target data and also supported by GretagMacbeth software.

Go to the next section: Image Inspector