Colour setup

Discussion in 'Photoshop' started by Peter Detheridge, Jul 23, 2003.

  1. 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. 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.
    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.
    The maual also gives instructions how to calibrate the scannert using b&w
    and colour targets to the printer and or application(egPS).

    PS also offers the ability to Assign a Profile. One does exist for the HP
    Scanjet IIC (model below mine).

    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)
    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.

    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

    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.

    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

    Perhaps all I am asking is what is the correct workflow for scanning

    Any advice will be gratefully received.
    Peter Detheridge, Jul 23, 2003
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  2. 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
    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.

    Peter Detheridge, Jul 24, 2003
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  3. Peter Detheridge

    Mike Russell Guest


    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

    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

    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
    Mike Russell, Jul 24, 2003
  4. Mike thanks for your assistance. I am familiar with curves and have been
    working on furthering my understading of how to work with the end points and
    gamma slope using the "s" curve etc. I have found this exercise useful for
    this and for understanding the use of the individual channels.

    As you say I now have a baseline to work to thanks to your pointers. I will
    now be more confident in proceeding with my photo retouching.

    Peter Detheridge, Jul 24, 2003
  5. Peter Detheridge

    Mike Russell Guest


    Congratulations on the detective work!


    Mike Russell
    Mike Russell, Jul 25, 2003
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