CONNECTING THE LAST DOTS
Many of them report that their monitor is calibrated and profiled and they are following a color managed workflow. But my response has been that is not a solution because there is only color information in profiles and density information is actually in the image file being printed. so a color managed workflow is really incidental and not the cause of the prints too dark problem. Well, that is true as far as it goes.
Since finishing my report on how to avoid prints too dark I mentioned above, I have been testing a new LCD display, which incidentally is adjusted to a white luminance of 90.0 CD/m2. And as part of my testing I have gone to my CD collection of archived image files made in the last 2-3 years since I have been using LCD displays. Then my displays were set at a white luminance of 120.0 CD/m2 which then I had found I could not go below much without adversely affecting image reproduction quality on-screen, and it was also the default recommended by many color management companies like X-Rite. With a 30 point difference in display brightness, obviously the images on CD did not appear to have a desirable brightness on-screen, and needed to be adjusted if I expected them to print at an ideal density. But not only did I need to adjust the image brightness of theses saved image files, when I did lighten them to look right on my screen set at 90.0 CD/m2 I found I also had to adjust the level of saturation. That got me thinking that maybe brightness/density are in fact dots that need to be connected to make color management function fully.
If the goal of color management is to match color between display and print output, then if you took the measurement of a color that’s on the screen of a calibrated and profiled display, and then in the print out, measured the color with a spectrocolorimeter, what we used to call a reflective color densitometer, the RGB values measured should be the same. But if you are getting dark prints obviously there will be a big difference in the RGB numbers between the image on screen and print, so color management isn’t working. In other words the normal functioning of the popular monitor/display calibration and profiling software and sensor is not providing a profile that CAN match with print output if the monitor is a typically bright LCD display.
What is required is the integration of the display white luminance adjustment into monitor calibration and profiling so it matches the white of printing paper. In other words if you are working in Photoshop and you open a new white blank image, its brightness must be the same value as the white of the paper you will be printing on. When I have suggested this some have argued paper white can vary depending on how much light it is reflecting, how bright the illumination source is. But there is a standard if you want to measure paper white that is used for instance in the illumination that is provided in print viewing booths used in pre-press. For pre-press the default white luminance for a display to provide a match is 80.0 CD/m2. But for pre-press you are dealing with papers that are generally not as bright white as high quality photo printing paper for an inkjet, so I have extrapolated that difference applied to digital photography and have assumed a display white luminance of 90.0 CD/m2, and my test printing has confirmed it works.
The bottom line is color balance, saturation and brightness are dots that must be connected and matched for color management to function and provide the predictable results the system is intended to accomplish. But standard monitor calibration and profiling hardware and software is often incomplete and does not connect all the dots and match them, so many users have been led astray and as a result get too dark prints.
If you have a comment, they are welcome, so please post it. If you have a question you want me to answer please address an e-mail to David B. Brooks at: firstname.lastname@example.org
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