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ignacior21653468
ignacior21653468
Participant
February 28, 2023
Question

IRB inside a TIFF image file

  • February 28, 2023
  • 1 reply
  • 1375 views

Hello,

I´m generating a TIFF image for an hexachrome printer and would like somebody could confirm a couple of things:

1) Does Photoshop support Separated (TIFFTAG_PHOTOMETRIC=PHOTOMETRIC_SEPARATED) images with more than 4 planes?

Therefore, what I have done is creating a TIFF with extra alpha channels. Hence my next question:

2) In order to open the previous TIFF without loosing information, is enough if I include the following IRB´s: 0x03ee, 0x0415, 0x041D, 0x042B, 0x0435?

3) I can include alpha channels color information in 0x042B, in RGB, HSB, CMYK, LAB,..l alternate colorspaces. However, IRB 0x0435 contains information in LAB for display. What is the difference between them, and how does current color settings affect the alternate colors, if at all.

 

Thanks for your help,

   Ignacio

 

This topic has been closed for replies.

1 reply

Kevin Stohlmeyer
Community Expert
Kevin StohlmeyerCommunity Expert
Community Expert
February 28, 2023

Hi @ignacior21653468 

This post may help: https://community.adobe.com/t5/photoshop-ecosystem-discussions/how-can-i-do-separations-in-more-colors-than-cmyk/m-p/11640873

 

ignacior21653468
ignacior21653468Author
Participant
February 28, 2023

Kevin,

Thanks for the link, but it does not help too much. My request is rather technical, for I am the one generating the TIFF file and Photoshop is the recipient of it. I mean, the file is neither going to be generated nor separated by Photoshop. But is has to be readable by Photoshop. There is a special/private TIFF tag  (0x8649) that Photoshop uses to embed additional information (layers, selections, alpha channels) in what they call Image Resource Blocks (IRB).
Those Blocks are documented in "Photoshop File Formats Specification" and in Appendix A of "Photoshop API Guide", but that information is not complete.
My questions still hold. Thanks for trying.

    Ignacio

Stephen Marsh
Community Expert
Stephen MarshCommunity Expert
Community Expert
February 28, 2023

@ignacior21653468 

 

Most folk here are end users, not third party software developers, so I can only suggest that you try it yourself. If you don't have access to Photoshop, we can help to test the file.

 

So apart from the basics, you probably need to post in an appropriate developer forum:

 

https://forums.creativeclouddeveloper.com/

 

https://developer.adobe.com/developer-support/

 

https://developer.adobe.com/xd/uxp/community/

 

 

 

 

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