Monitor Profile and Color Management

<p>I thought that I had a reasonable understanding of color management, and the role of the monitor calibration and profiling. That is, I thought so until I read the following statements in a very reputable online photography forum. The thread dealt with color management (or lack thereof) in various internet browser applications.</p>

 

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<p>"Until your post I didn’t know that any browser supported monitor profiles."<br>

"Firefox also uses the monitor profile ..."<br>

"In short, the profile has a much higher precision level. But it is not system-wide, it is used only by some applications. Color managed applications like Photoshop or Firefox convert the document profile to the monitor profile and sends it off to the display.<em> A non-color-managed application, like Internet Explorer, just sends the numbers straight through without any correction for the monitor." </em></p>

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<p>I have gone back and reviewed Jay Kinghorn's Color Management Primer, and believe I have a fair grasp of what he has written. My initial impression remains that, once a monitor was caibrated and profiled using a modern hardware plus software package, the custom profile was automatically loaded at boot time and set as the default monitor profile (either by the O/S or a special loader program). Thus I assumed the custom monitor profile was available to and used by whatever software (color managed or not) was employed to display an image. </p>

<p>As regards non-color-managed applications, I assumed that these were so described because they failed to recognize and compensate for the color space with which an image is tagged. I have always been aware that Internet Explorer (and perhaps most browsers) did not honor the color space tag attached to an image and assumed all images (tagged or not) to be in sRGB color space. </p>

<p>What surprised and confused me in the above statements is the suggestion that all non-color-managed applications bypass (or effectively ignore) the monitor profile. Clearly a custom monitor profile will not suffice to correct for a wrong or absent color space tag attached to an image, but I am truly confused by the suggestion that the profile is completely bypassed by non-color-managed image viewers. Since some device profile must be used to display images on the monitor, what is used in place of the custom monitor profile?</p>

<p>Can someone enlighten me?</p>

 

<p>Mike,<br>

You might want to look into <a href="http://www.earthboundlight.com/phototips/firefox-color-management.html">this</a> and into <a href="https://developer.mozilla.org/En/ICC_color_correction_in_Firefox">this</a> to clarify this issue.</p>

 

<p>Your source is confused... Its monitor profile (device dependent) vs colour profile (device independent). Colour aware applications (ie Firefox) are reading a file embedded colour profile (sRGB, AdobeRGB, etc) to determine the colour model it should use to render the per pixel values. Whether that looks accurate on your monitor is dependent on whether your specific monitor was calibrated (which generates a monitor profile). Monitor calibration is an OS level transformation of colour values as they are being sent to the monitor to basically ensure that colour value 'Y' is actually displayed as visible colour 'Z'. On the other hand, the colour profile is used by the colour aware application to ensure that pixel value "X" in the image file is rendered to colour value 'Y' as its sent to the monitor.</p>

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<p>Since some device profile must be used to display images on the monitor, what is used in place of the custom monitor profile?</p>

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<p>You can't control what others see of your images viewing on non-calibrated monitors and non-color managed browsers online, so don't waste one minute of your time concerned about this.</p>

<p>If it bugs you that much, do what I do as a test of your uploaded sRGB tagged images by going to Best Buy or any other big box store and viewing them on any off the shelf PC connected to internet in both a color managed and non-color managed browser. Safari is always color managed and does use the canned (most likely on Best Buy PC's) or custom display profile and there again is a variable for lack of color control.</p>

<p>The reason is there are two components of a custom display profile...<br>

1) The RGB correction curves (LUTs) downloaded to the video card that force neutral gray throughout the display's 255 tonal scale from black to white. Most off the shelf displays look different in white balance, some bluish, some greenish, some reddish requiring correction.</p>

<p>2) The measured and mathematically calculated RGB/color temperature colorant descriptors that all color managed apps use to maintain a constant appearance of hue/saturation of individual colors in an image THAT IS TAGGED with the output color space which in this case is sRGB.</p>

<p>The second component won't be used by non-color managed apps <strong>(another variable)</strong>.<br>

Also both older and newer non-calibrated/profiled displays will vary in intensity in hue/saturation (called color gamut) where both color managed and non-color managed browser will still show slight color errors because the <strong>often inaccurate canned profile</strong>, the non-corrected LUT AND the unmeasured color gamut compounds all this adding even more <strong>uncontrollable variables</strong>.</p>

<p>Tagging all your web images with sRGB is your only assurance for future browsers to implement color management and even then the display must be calibrated/profiled for this to work. </p>

<p>I just viewed my sRGB tagged online images on the new iPad using Safari at Best Buy and for a non-calibrated device they look better than I expected. Not so on Best Buy's off the shelf PC's.</p>

<p>There are two steps: Calibration and profiling. The LUT is loaded to affect the display but the profile may or may not be recognized and used by some applications. Applications that are ICC aware have access to the display profile and they understand the document’s embedded profile and use both pieces of data to produce a preview. So LUT without profile awareness isn’t useful. </p>

<p>So related to this is the oft comment "forget about trying to get your image perfect for non color-managed applications".</p>

<p>There aren't a 1000 applications we use. I use IE, Chrome, that's it. For images Facebook, Photo.net. Their behavior is completely consistent. So if we know exactly what they do can't we then have a formula to produce great results all the time on them? (assuming calibrated monitors)</p>

<p>My thanks to all who responded.</p>

<p>My initial impression remains. </p>

<p>A monitor, once properly calibrated and profiled, will "utilize" the custom device profile regardless of what application (color managed or not) is invoked to display an image. Obviously when an image has no embedded color space, or the application fails to recognise and respond to the embedded color space tag, color management will fail. The efficacy of the device (monitor) profile depends on the accuracy of the data presented to it. It seems to be the old case of "garbage in - garbage out".</p>

<p>I believe the statements quoted in my first post have been made by persons who failed to distinguish the role of the monitor profile and that of the color space "awareness" of the browsers.</p>

 

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<p>A monitor, once properly calibrated and profiled, will "utilize" the custom device profile regardless of what application (color managed or not) is invoked to display an image.</p>

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<p>Nope. For a color managed path, the application <strong>has</strong> to know the profile exists and uses the profile, along with it’s knowledge of the document color space to produce the correct preview. Non ICC aware applications have no idea about either (display profile or document profile). DISPLAY USING MONITOR COMPENSATION is therefore not part of the color managed path. </p>