The Patch Tool Display Check Tool

Selecting the PatchTool display check tool opens the following window.

Display Chk Window

The Display Check tool can make display measurements from preset patches (Quick-Test menu) or a color list opened in PatchTool (PatchTool file menu). Quick-Tests, consist of patches defining a grey scale ramp with or without ramps for the R, G, and B primaries. As Source and Destination profiles, you select the source files RGB-space, (AdobeRGB for many of us) and the destination files RGB-space (your displays ICC profile).

After allowing sufficient time for your display to warm up, (1 hour) you position your color measuring device over white window and run the test.

Simple Results

I started out with a simple test using the Macbeth color checker card file whose reference data is provided with PatchTool, several digital versions of targets used for proofing are also provided.

Macbeth patches

The results are displayed in the PatchTool Compare window shown above. The color squares shown are the color patches in the Macbeth color checker. The reference and measured colors are shown simultaneously in each square, separated in two triangles; the top triangle shows the reference and the bottom one the measurement. The illuminat setting is the white point of my display 5500° K. The user selectable yellow and red borders show, when a certain threshhold Delta E has been exceeded. Here, no patch Delta E is greater than 1.0 (red border). No patch has a difference which can be detected by a typical user, even in direct AB conditions. Seven patches have a Delta E between 0.5 and 1.0 (yellow border). A patch in this area has a color difference so small, it might be detected by a trained observer, in a direct AB test, under perfect viewing conditions. Basically, the Macbeth color checker is displayed on this monitors about as good as any one could hope for. If you look closely, you can see a tiny difference in the light green patch, second up from the lower left.

Clicking on the stats tab, gives a second statistical view,with the results displayed in histogram format.

Macbeth stats

The Whole Enchilada

This simple check looks good, but it has a small color range. How many colors do we really need to do a thorough test. Fortunately for us that question has been answered by the SWOP/IDEAlliance requirements. This group has come up with the range of printable colors deemed to be a thorough test. The vaunted Apple Cinema displays are deemed SWOP compliant, because after calibration, they pass this test. This test contains 1617 color patches! I picked the Coated 3 variety of this test, which is designed for high end publication printing on glossy paper and ran the test. Some 40 minutes later, voila !

SWOP compare

The default patch view, showed the results. No patch had a Delta E >4.0, only 11 patches had a Delta E >2.0 and these were mostly in the difficult to display very dark neutral tones. Once again, if you look very closely you can see the tiny color differences, mostly in the darker patches.

For an even more detailed look, we can click on the Stats tab.

SWOP stats

You can see the highest Delta E's encountered were on the order of 2.5. The average Delta E for all patches was 0.77. Any Delta E less than 1.0 is almost invisible. This is a very, very good performance. The SWOP standard allows individual color errors as high as 6.0 . It also requires the average Delta E of all patches be ≤ 2.0. My 30" HP LP3065 passed with flying colors. No pun was intended!

Closing Thoughts

PatchTool also has the capability to test your printer and see if its meets SWOP proofing color standards. That feature however, is beyond the scope of this review.

Do you need PatchTool? Only you can answer that question. If you are a PC owner, and wonder if your computer display meets the SWOP certification standards, passed by the Apple Cinema displays, the answer might just be yes.

Available in both Mac and Windows versions, PathTool 2.3 is can be purchased for $75.00. An evaluation version is downlaodable from BabelColor.

Back to Part I


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