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Notes on preparing images for printing

Introduction to Colour Space conversions: http://www.cambridgeincolour.com/tutorials/color-space-conversion.htm

Takeaways:

  1. Perceptual and relative colorimetric are the only two rendering intents we are interested in
  2. Perceptual COMPRESSES the range so that all colours fit within the colour range of the output device
  3. Relative colorimetric leaves all colours that fit alone and CLIPS those outside to the closest colour within.
Video Adobe Photoshop Soft Proof and Gamut warning: http://youtu.be/7WD48D4H2Os
Takeaways:
  1. Undesired colour changes introduced by rendering intents can be eliminated by manually identifying and modifying image colours.
Technique for colour preparation:
  1. If starting from Lightroom: Edit in Photoshop
  2. In Photoshop: Edit > Preferences > Transparency & Gamut
    1. Under Gamut Warning, click the colour box to display the colour picker.  Choose a warning color not present in the image, click OK.
  3. View > Proof Setup > Custom
    1. Device to simulate: Choose profile for printer/media/ink combination
    2. Preserve numbers: clear
    3. Rendering  intent: Perceptual OR Relative Colorimetric
    4. Black point compensation: select
    5. Simulate paper colour & black ink: clear both
  4. Toggle back and forth with CTRL+Y
  5. Toggle gamut warning  with SHIFT+CTRL+Y
  6. Modify out of gamut colours using masks with one or more of the following types of adjustment layers. Different areas may require different fixes so put each on a new layer
    1. Selective colour
    2. Hue/Saturation
  7. To eliminate every single out of gamut pixel may cause too much damage to the image quality. A possible solution to this is to eliminate the bulk of out of gamut pixels using the above techniques then print using the RC intent to clip those odd pixels into gamut whilst not affecting the bulk of the image. Run a test print to be sure.
Technique for printing:
  1. Using Image Size convert to 300 dpi at the final size.
  2. Apply output sharpening (e.g. http://www.pixelgenius.com/tips/schewe-sharpening.pdf)
  3. Edit > Convert to profile
    1. Destination Space Profile: Choose profile for printer/media/ink combination
    2. Engine: Adobe
    3. Intent: Relative colorimetric (if you are using the clipping method, or Perceptual if that works better)
    4. BPC: select
    5. Flatten: select
  4. Image > Mode > 8 bit
  5. Save as tif, no compression.
  6. Send to lab/printer.

 

 

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