Enhancement: support custom (non sRGB) output ICC profiles and colourspaces

This will convert pixel values using a provided ICC profile and attach that profile to the output image metadata.

It should assume the profile is RGB. If e.g. a CMYK profile is required, toColourspace must be used in addition.

Convert to and attach custom RGB output profile (proposed):

sharp(input)
  .withMetadata({ profile: '/path/to/rgb.icc' })
  ...

Convert to and attach existing RGB output profile (proposed):

sharp(rgbInput)
  .toColourspace('rgb')
  .withMetadata()
  ...

Convert to and attach custom CMYK output profile (proposed):

sharp(input)
  .toColourspace('cmyk')
  .withMetadata({ profile: '/path/to/cmyk.icc' })
  ...

Convert to and attach existing (or default if missing) CMYK output profile (proposed):

sharp(cmykInput)
  .toColourspace('cmyk')
  .withMetadata()
  ...

The icc_export, or icc_transform when no input profile, operation can be used for this.

The current existing behaviour, as in the following examples, will remain.

Convert to sRGB without embedded profile (existing behaviour):

sharp(input)
  ...

Convert to and attach existing sRGB output profile (existing behaviour):

sharp(input)
  .withMetadata()
  ...

See #1324 for custom input profile support.

See #218 for previous discussion on this and related features.

See #734 for a related enhancement that this might address.

[lovell]

Every issue tagged as an enhancement, such as this, represents a future possible enhancement; there is no “ETA”, “roadmap” or “timeline”.

On behalf of all sharp users I am always very grateful to anyone that helps implement such enhancements, either by using their own time to work on and submit a pull request or by offering to pay for my time to do likewise.

[randyridge]

Any movement on this? I’d simply like to replace the sRGB.icc with some Compact ICC Profiles in certain scenarios…