Browser Gamma Correction Test Page

ICC-profile-labelled PNGs (1/1.0) on CSS Colors

This page was created in order to test the self-consistency of web browsers' gamma correction. In brief, if they gamma-correct CSS colors on non-sRGB systems (which is required, according to the CSS-1 specification), then they should also gamma-correct unlabelled images in the same way. Alternatively, if they don't gamma-correct CSS colors (which violates CSS, although it is allowed for HTML colors), then they should not gamma-correct unlabelled images, either. In the latter case, however, labelled images (such as PNGs with a gAMA, cHRM, sRGB or iCCP chunk, including the ones on this page) are unlikely to match the CSS colors across all platforms.

This version of the page uses PNG images labelled with an ICC profile (and no gAMA chunk) as being in the gamma 1/1.0 (linear) color space, and CSS colors for the backgrounds of the table cells. The ICC rendering intent is "ICC-absolute colorimetric." The images will be distinct from the cell backgrounds if the browser fails to gamma-correct both the PNGs and the CSS colors, and the system is sRGB (such as most Windows- and Unix-based PCs); or if it gamma-corrects only one of the two on a non-sRGB system (such as most Macs, SGIs and NeXT cubes). If the browser gamma-corrects both (and does so correctly!), the edges of the images will be invisible on all systems. This will also be the case on sRGB systems if the browser gamma-corrects only the PNGs, however.

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