Peter,
Good to see you’re narrowing the problem down bit.
The fact that re-assigning the generic Deskscan profile increases the red cast makes me wonder if you have a system wide profile installed. Assigning the profile a second time in Photoshop would make things exactly twice as bad.
On my Win2k system this is accessed via Start>Settings>Control Panel> Scanners and Cameras. Depending on your version of windows, you may see something different, like a separate Color control panel.
Click on the properties for the profile for your scanner and see if you, or the HP installation software, have already assigned the generic profile. If so, konk it on the noggin and you may see your scans clear up.
It’s not normal for a scanner to have as much of a red cast as you are describing. I’d suggest removing and re-installing the device, or trying your scanner out on a different system to see if the color cast follows the scanner.
It’s relatively unusual for scanner hardware to fail in this way. So I would look hard at software issues before starting to blame the hardware, though that is certainly a possibility.
—
Mike Russell
http://www.curvemeister.com http://www.zocalo.net/~mgr http://geigy.2y.net Peter Detheridge wrote:
Well I got that wrong. Using Mike’s advice I imported the wedge file with skin tones and printed directly to my printer. The image on the monitor showed no cast and neither did the printed output. Surprise! Using the output as a target I scanned it into Photoshop (with calibration set to "None" and no other scanning software adjustments) and the reddish caste became very apparent. Hence I now realise my scanner is the culprit. I then scanned again using the calibration I had set up in the HP Deskscan II software previously (having re-checked the settings etc) but this exeacerbated the red caste. Sticking with the uncalibrated scan, I applied the Scanjet IIc profile when opening the document and this seems to have removed most of the cast although the image was far from a perfect match to the original photo. However using Curves I resolved that fairly readily with the usal tonal corrections.
I guess I now have a choice. Either use the scanner software to modify the color setting during the scan (not very accurate) or continue on as described above, that is leave the scanner software settings flat and make all the adjustments in PS. I will experiment some more with the profiles to see if its better convert all documents to the Adobe RGB working space and then make adjuystsments or use the genercic scanner profile and make adjustments from there.
Regards,
Peter
"Peter Detheridge" wrote in message
Mike,
an enormous reponse but extremely useful. Thanks for taking the time to explain all of this, its clearly a complex topic but you have answered all of my queries.
I think I have narrowed the red cast to the printer and maybe this is why when I use the calibration the red seems exagerated however using the tonal corrections the final output seems OK. However, I will confirm this using the information below.
For information, I do use flat settings when scanning make all my corrections in PS and I scan using a greyscale wedge regularly.
Thanks again for such an informative response.
Regards,
Peter Detheridge
"Mike Russell" wrote in message
Peter Detheridge wrote:
I use an HP Scanjet 3C for most of my photo image work. I have just upgraded to PS7. I am confused as to how to colour management is meant to work.
Indeed you are not alone. Ever hear of the ancient Greek problem of circling the square, using only a straightedge and compass? Color management – meaning the use of custom profiles at every possible step in the imaging process, can be like that.
Though profiles can have substantial benefits, particularly in a multi workstation environment, setting up profiles for a smaller setup may have no benefit because it can be as complex as the problem it is designed to solve..
Here’s why:
Documents created from the scanning process appear to have no profile embedded. I have multiple options eg use the default colour space (Adobe RGB) and no colour management. The images look ok on screen although they do not print true on my HP5550 Deskjet.
Do the prints have a color cast, and if so, at what point in the process does that happen? Is is after the scan, or after printing. To isolate this, print a grayscale step wedge visually check it for casts. If there are any, print it from another non-color managed app, such as explorer or
netscape. It’s easy to make a step wedge, however until you have your color setup shaken down, I suggest you download the one from: http://www.zocalo.net/~mgr/DigitalPhoto/digital_test_strip.h tm . This step wedge is also useful to check your display settings – it should be free of color casts when opened in Photoshop.
My scanner manufacturer make statements like the reflectance line of this scanner is set to enhance bright colours, greater saturation etc. If I want "true" colour to scan with specific highlight and shadow points.
Scanner manufacturers do tweak their colors – this is to be expected since they rightly consider themselves to be responsible for the "out of box" experience of their customers. Printer manufacturers do this as well. Epson, for example, has a PhotoEnhance mode that modifies the appearance of the printed image.
The maual also gives instructions how to calibrate the scannert using b&w and colour targets to the printer and or
application(egPS).
This involves setting controls in the scanner software?
PS also offers the ability to Assign a Profile. One does exist for the HP Scanjet IIC (model below mine).
Fine, but if you use this be very careful to leave your other scanner settings "flat" – no other color correction or enhancements in the scanner software. Strictly speaking, you should not even set your black and white points, though in practice it turns out this is pretty much OK.
Here’ how I have it set up currently and producing "OK" results. I scan using the profile I generated using the printed targets through photoshop. The colours on the monitor are dreadful (red overdose and dark)
Before doing anything else, you need to address the red look to your scans. See if the grayscale wedge I mentioned above looks neutral on your screen. If it does, then your scanner profile is incorrect, and you need to keep trying until it gives you an image whose grays are gray.
I then assign the profile and colours normalise somewhat. I then use curves to do the ususal tonal correction etc and print. To my surprise this seems to give fairly accurate colour rendition. IE the printed image is true to the original and to my monitor.
Basically your color profile messed up your image, took your weeks pay, bonked you on the noggin, and dumped you down the river. You are now having to paddle back upstream, and when you get to town your profile will have spent your paycheck on cheap booze and cheaper women. Now I ask you, is your color profile is a good friend to go into to town next week with, or not?
Question is, am I trying to get too clever with this (I am only an amateur). Do I need to calibrate the scanner at all given the Colour Mgt capability of PS7?
Short answer – no, you do not need to calibrate your scanner. It may save you work to do so, or it may cause giant headaches. In any case you can scan and print your images with impunity provided the results appear good in your judgement. If you do calibrate your scanner, then make sure the profile was created using flat scanner settings or you may get something worse than no profile at all..
In either event, do I need to assign the profile for the scanner to the image after its scanned and which option should I work with (eg none, Adobe RGB colour space)? Ie No profile, no calibration.
In general you would assign the profile to the scanned image. However, if you have already used the profile to modify the scanned colors, you decidedly do not want to do this. For example, if you have already entered the profile into the the operating system’s scanner color settings, or the scanner software itself, then assign the Adobe RGB profile to each newly scanned image.
Please note I have calibrated the monitor using Adobe Gamma and using the custom settings provide by ADI (ADI5G). The monitor has a gamma of 2.85
One warning here about a common pitfall. If you checked the box that allows you to adjust the R, G, and B gamma sliders separately, then it is possible that the reddish cast you mentioned before is due to gamma settings. I suggest you keep the three gamma sliders locked together as a single slider for the time being until you are sure about the rest of the process..
Perhaps all I am asking is what is the correct workflow for scanning images??
Whether or not you use profiles, the most important items on your color agenda should be:
1) correct white and black points
2) overall lightness and darkness of the image
3) getting rid of color casts
Any advice will be gratefully received.
Do look at Ian Lyon’s articles on color management and setup: http://www.computer-darkroom.com/
I would finish with the following: "Profiles schmofiles". At the end of the day, if you can scan an image and get neutral grays, with good black and white values, and correct overall brightness, how far off can you be?
Happy scanning!
—
Mike Russell
http://www.curvemeister.com
http://www.zocalo.net/~mgr
http://geigy.2y.net