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Q: cmsDoTransform(): using same buffer for in and out #93

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LebedevRI opened this issue Aug 8, 2016 · 2 comments
Closed

Q: cmsDoTransform(): using same buffer for in and out #93

LebedevRI opened this issue Aug 8, 2016 · 2 comments

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@LebedevRI
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Hi.

Unfortunately LittleCMS2.7 tutorial.pdf is not verbose-enough.

I would like to get a clarification about:

It is safe to use same block for input and output, but only if the input and output are coded in
same format. For example, you can safely use only one buffer for RGB to RGB but you cannot use
same buffer for RGB as input and CMYK as output.

In particular, that does mean that i can not use the same buffer to convert from TYPE_RGBA_FLT to TYPE_LabA_FLT, but i can use the same buffer to convert from TYPE_RGBA_FLT to TYPE_RGBA_FLT?
@mm2
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mm2 commented Aug 8, 2016

You can reuse the same buffer as long as the output pixel size is same as input pixel size. So RGBA_FLT to LABA_FLT is ok, but CMYK_FLT to LAB_FLT is not.

The reason is the engine keeps two pointers, one for input and other output. If the output pixel size is less then the input pixel size, input will be overwritten when applying color transform.

@mm2 mm2 closed this as completed Aug 8, 2016
@LebedevRI
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You can reuse the same buffer as long as the output pixel size is same as input pixel size.

Awesome!
Thank you for clarifying this. :)

LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_sse2_lcms2_proper(): no need for tmp buffer
031b26b 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_sse2_lcms2_bm(): no need for tmp buffer
e70a9c8 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_lcms2_bm(): no need for tmp buffer
2bbde0a 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_lcms2_proper(): no need for tmp buffer
c7262bf 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_sse2_lcms2_proper(): no need for tmp buffer
a82a719 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_sse2_lcms2_bm(): no need for tmp buffer
132ef53 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_lcms2_bm(): no need for tmp buffer
6d0fa5f 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 8, 2016
@LebedevRI
Colorin: process_lcms2_proper(): no need for tmp buffer
10e592e 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process()
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 9, 2016
@LebedevRI
Colorin: process_sse2_lcms2_proper(): no need for tmp buffer
9f71be3 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process(): no need fo
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 9, 2016
@LebedevRI
Colorin: process_sse2_lcms2_bm(): no need for tmp buffer
393cd41 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process(): no need fo
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 9, 2016
@LebedevRI
Colorin: process_lcms2_proper(): no need for tmp buffer
1ca94bf 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process(): no need fo
LebedevRI added a commit to LebedevRI/darktable that referenced this issue Aug 9, 2016
@LebedevRI
Colorin: process_lcms2_bm(): no need for tmp buffer
3fe64ca 
mm2/Little-CMS#93

Alternatively, i should have at least factored alloc
out of all the loops, like in lens.c process(): no need fo
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@LebedevRI @mm2