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Weekly Chatter:ACR Color Space?
Monday September 20, 2004
by Imaging Revue Experts and Staff

Each and every week, Imaging Revue offers non-members a tantalizing taste of the information available in our forums. Make sure to check out the entire list.

Weekly Chatter:Win XP Service Pack 2
Monday September 13, 2004
by Imaging Revue Experts and Staff

Each and every week, Imaging Revue offers non-members a tantalizing taste of the information available in our forums. Make sure to check out the entire list.

Unsharp Mask Demystified
Thursday September 9, 2004
by Ellen Anon

"Ask any number of digital photographers the settings they use in Photoshop’s Unsharp Mask filter (USM) to sharpen their images and that’s the number of different responses you are likely to get. Because of this a significant number of people turn to plug-ins to do their sharpening for them. However once you understand the basic principles involved in using the USM it is fairly easy to make it work predictably and effectively."

Weekly Chatter:External hard drive recommends
Tuesday September 7, 2004
by Imaging Revue Experts and Staff

Each and every week, Imaging Revue offers non-members a tantalizing taste of the information available in our forums. Make sure to check out the entire list.

ImagePrint 6 Notes
Thursday September 2, 2004
by Mitch Alland

I am pleased to see that the new ImagePrint manual for v6 is a great improvement over earlier versions and is, in fact, excellent. The extensive Troubleshooting Guide section is a good addition. Also, as program installation has been simplified, I believe that most questions on IP problems that come up on online forums can now be answered by suggesting, in the best Unix tradition, that the user "look it up in the manual...." These notes are based on ImagePrint 6 build 1.08. If you are using a later build some of the issues and glitches discussed below may have been fixed, as ColorByte is aware of all of them.

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Color Management/WorkFlow > Workflow > Digital back profiling: BetterLight

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AuthorSubject: Digital back profiling: BetterLight   [Go to Bottom of Page]
Sarah Smith
Posted on Mon Jan 19, 2004 4:33 PM

I have a BetterLight Super 6K scan back that is used for art copy (used with North Light's HID Copy Lights - Daylight balanced). I've been using a standard MacBeth ColorChecker (24 patches) with InCamera's Plug-in software to create the profiles. Although the files are coming in relatively well, there are definitely some problem areas (greens turn grey, etc.). I realize that there are limitations, but I would like to get the color as accurate as possible in order to streamline the workflow and avoid having to do the same color corrections every time in Photoshop because the capture is off. So, my questions are:

1) How consistent does the exposure need to be in order to maintain the validity/usefullness of the profile? Everything I've learned about profiling printers & monitors says that if you change ANY setting that was in place when the profile was created, you are invalidating the profile. I want to know if this is also true with a digital camera back, or is there some lee-way for exposure "tweaks" based on the artwork? (I might want to expose slightly differently for a deep dark oil painting than for a watercolor with light washes, for example.) Should I keep the values in the white and black patches (endpoints) constant but feel free to adjust the tonal curve for the middle values? Do I need to keep everything - ISO, line time, endpoints, tonal curve - EXACTLY the same as when I captured the target for the profile? If there is some "wiggle room", where is it and how much do I have (10 points, 50 points)? Which areas should I strive to keep the same every time (white, black, middle grey)? How close do I need to be?

2) What is the best way to check the quality of the camera profiles after they are created? I've looked at them in my viewers (ColorShop X, Monaco's Gamutworks) and have applied them to synthetic targets (i.e. Grainger Rainbow). I've considered opening a file of the ColorChecker, assigning the profile(s) to it, and comparing it to the original file to evaluate accuracy as well...

3) When should I resort to editing the profile? When should I edit versus going back to the beginning and re-profiling? Which editor would give me the best results? With printer profiling, if I see major issues I go back to the beginning and start over rather than trying to edit out the problems. I try to only edit as a fine-tuning measure. Should this be the way I treat the camera profiles? I have so few choices (basically exposure) on the front end, so I'm guessing I might be forced to make bigger moves in editing to get things right...

4) Are there any areas of color that are inherently going to be off with the CCDs? I've read Robin Myers paper on color accuracy, which goes over a technique of using both the daylight and tungsten infrared filters (rather than one or the other) in order to get better results with certain colors (i.e. cobalt blues). The profile made with both filters has better magentas and yellow-greens than the daylight filter alone, but it suffers a bit in the reds and oranges. However, my working space (Adobe 1998) doesn't contain any of those reds and oranges anyway so...

5) Which rendering intent is used when I choose to assign the camera profile, then convert to my working space? Is it the default intent in my Color Settings in Photoshop? Knowing that my working space is bigger in some areas (yellow-greens) and smaller in others (dark blues and reds), which rendering intent am I better off using in this conversion? Should I consider using a bigger working space?

I know that camera/back profiling is a highly-debated topic, but I do have one of those consistent lighting situations that it seems would lend itself well to profiling. I look forward to what you all might have to say!


... this thread contains expert advice from Andrew Rodney.




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