implement CalGray / CalRGB colorspace

[sbarman]

They are currently set to DeviceGray and DeviceRGB, which may give slightly different colors

[kkujala]

I have WIP for CalGray colorspace in here: https://github.com/kkujala/pdf.js/commit/a40b0ce35e1bf411d6064db6ac4ad7a02680df8d

It is not ready yet but it is much more inline with adobe than the existing implementation. Basically I would like to have some feedback if this is on the right track and some help in few issues. I've attached a manually created pdf that be used compare against other implementations. I'll extend the pdf later on with more pages.

Issues that I have.

• I cannot get exactly same colors when comparing to adobe in the simplest of cases (page 1). I suspect that I should use a different formula.
• When using higher gamma value (page 2) then the colors turn to black much more aggressively. Again likely due to formula.
• BlackPoint stumps me (page 3). How an earth should it be implemented.

So any help would be appreciated. @yurydelendik, can you help?

[yurydelendik]

CalGray is implemented in #3577

[timvandermeij]

Just to add more information: CalGray has partially been implemented in that patch. BlackPoint is not supported yet.

[timvandermeij]

Closing since both are implemented.