Ralph's Test Pattern Collection

Test patterns are useful for many purposes, and specially for calibrating computer displays. I've collected some here that I often use when faced with display problems or issues with color image processing algorithms.

The accurate display of information, specially color information is a complex technical topic involving detailed transfer function modeling and details of human perception. It deserves a far more detailed treatment than this simple collection. However, these images are of use to me given my current state of knowledge. I am still learning about this topic.

[convergence.png]
A pattern I generated long ago to help converge old Sun CRT displays. You must insure that this image is displayed at its fill pixel-for-pixel resolution, and then you have to adjust the alignment of the RGB guns to make the dots and lines and clear as possible.

[spectral-examples-jpg] [spectral-examples.tif]
A composite image of several spectra and some color patches to get a quick all-in-one view, and allow comparison of the validity of the various spectra.

• The "Normal" spectrum shows the wavelengths
• The GIMP gradients generated easily in GIMP and have been stretched to match the gradient above it. A gray scale ramp is included.
• The Wikipedia Spectrum upper is a reduced intensity version of the one below it.

[wiki-spectrum-reduced.png] [wiki-spectrum-full.png]
These two images are protected under the Creative Commons license came from here and here.

[gamut1.jpg]
This convenient diagram show how various media only show certain ranges of color. It is not a great test pattern, but could be useful. I found it here and here with no attributions, so I cannot determine the original source.

[cie-color-bag.png]
This is a classic CIE diagram that is emblazoned all over the web. It illuminates the difference between pure spectra colors with single wavelengths along the curved boundary, and all the colors that are mixtures within. One example is here.

Ralph's Home Page 2010-01-14