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Pancyprian Graphic Arts study materials
Pancyprian Graphic Arts study resources

Pancyprian Graphic Arts: Image Capture and Colour Management

Pancyprian Graphic Arts · Work through your exam, one topic at a time.

All guide sections

Image Capture and Colour Management

This domain covers how images are captured, how colour is described numerically, and how profiles carry that meaning between devices. Expect capture settings, bit depth, profile logic, rendering intents and colour measurement with tolerances.

Core rules

  • Capture: sensor size and pixel count set the ceiling; RAW stores 12–16 bits per channel and allows white balance and exposure recovery, JPEG bakes in 8-bit processing.
  • Bit depth: 8-bit gives 256 levels per channel and risks banding in gradients after heavy editing; 16-bit gives 65,536.
  • Illuminants: tungsten around 3,200 K, print viewing D50, displays D65; sRGB is defined with a D65 white point and gamma close to 2.2.
  • Colour management: ICC profiles map device values to a Profile Connection Space (CIELAB/XYZ). Assign changes the meaning of existing numbers; convert recalculates the numbers to preserve appearance.
  • Rendering intents: perceptual (compresses the whole gamut, good for photographs), relative colorimetric with black point compensation (keeps in-gamut colours exact, clips out-of-gamut ones - the normal choice for print), absolute colorimetric (simulates the paper white, for proofing), saturation (for business graphics).
  • Working spaces: sRGB for web, Adobe RGB (1998) for wider capture, ProPhoto RGB only for raw editing at 16-bit.
  • Measurement: densitometer for ink density and TVI, colorimeter for emissive displays, spectrophotometer for spectral data and spot colours. ΔE00 ≤ 2 is generally acceptable, ≤ 1 excellent.
  • Metamerism means two samples match under one light source and not another - always judge under the specified illuminant.

Worked example

A client supplies a brand colour as an sRGB JPEG (255, 0, 0) for coated offset. Convert to the Fogra39 output profile using relative colorimetric with black point compensation: in-gamut colours stay numerically exact, the saturated red clips because it sits outside the CMYK gamut. Measure the printed patch against the target: ΔE00 = 5, well over tolerance. Options, in order: check whether the brand allows a spot colour (Pantone 485 approximates the red and holds it consistently), adjust the build, or accept the difference and get written approval. Never simulate a spot with a four-colour build without the client's written sign-off.

Traps that cost marks

Assigning a profile when you should convert (numbers unchanged, appearance shifts); judging proofs under office fluorescents; running a monitor at 300 cd/m² and calling it calibrated; upsampling a web JPEG to 300 ppi and expecting detail; using absolute colorimetric for photographic separations.

Key points

  • RAW is 12–16 bit; JPEG output is 8 bit and irreversible.
  • Assign changes meaning; convert recalculates values.
  • Relative colorimetric + BPC is the default for print separations.
  • ΔE00 ≤ 2 acceptable, ≤ 1 excellent for spot match.
  • D50 for print viewing, D65 for displays; ISO 3664 viewing.
  • Pick the rendering intent from the image content, not habit.