[Cin] oiiotool

[Andrew Randrianasulu]

вт, 7 нояб. 2023 г., 21:46 Andrew Randrianasulu <randrianasulu at gmail.com>:

> oiiotool --stats -v /dev/shm/1.exr                       Reading
> /dev/shm/1.exr
>                /dev/shm/1.exr       : 4096 x 2048, 3 channel, float
> openexr
> channel list: R, G, B
>           chromaticities: 0.639999, 0.33001, 0.300004, 0.600003, 0.150002,
> 0.0599972, 0.3127, 0.329          compression: "zip"
>                                        PixelAspectRatio: 1
>                                            screenWindowCenter: 0, 0
>                                            screenWindowWidth: 1
>                                              oiio:ColorSpace: "Linear"
>                                              oiio:subimages: 1
>                                                      Stats Min: 0.005371
> 0.006256 0.006348 (float)              Stats Max: 117.000000 106.500000
> 104.500000 (float)
> Stats Avg: 0.746420 0.699325 0.674529 (float)            Stats StdDev:
> 3.869811 3.841790 3.957525 (float)        Stats NanCount: 0 0 0
>                                               Stats InfCount: 0 0 0
>                                                       Stats FiniteCount:
> 8388608 8388608 8388608                Constant: No
>                                                   Monochrome: No
>
>
> this is for gimp exported EXR
>
> cingg exported tiff says:
>
> Reading /dev/shm/1.tif
>                          /dev/shm/1.tif       : 4096 x 2048, 4 channel,
> float tiff
> channel list: R, G, B, A
>           compression: "zip"
>                 Orientation: 1 (normal)
>                        planarconfig: "contig"
>                             oiio:BitsPerSample: 32
>                               tiff:Compression: 32946
>                                 tiff:PhotometricInterpretation: 2
>
>  tiff:PlanarConfiguration: 1
>
> tiff:RowsPerStrip: 1
>
> tiff:UnassociatedAlpha: 1
>
> Stats Min: 0.265371 0.266256 0.266348 1.000000 (float)
>
>  Stats Max: 1.000000 1.000000 1.000000 1.000000 (float)
>
>  Stats Avg: 0.630706 0.600794 0.582030 1.000000 (float)
>
> Stats StdDev: 0.221808 0.214916 0.202718 0.000000 (float)
>
> Stats NanCount: 0 0 0 0
>    Stats InfCount: 0 0 0 0
>         Stats FiniteCount: 8388608 8388608 8388608 8388608
>
> Constant: No
>             Monochrome: No
>
> ====
>
> example usage from
>
> https://openimageio.readthedocs.io/en/latest/oiiotool.html
>
> wow, so oiiotool in itself a bit like imagemagick :)
>
> might make preparing some image sequences easier ...
>
>
> also, guess we better to note in manual that even if cingg outputs fp32
> exr/tiff values there are normalized to 0-1.0f as far as we can see.
>

https://docs.krita.org/en/general_concepts/colors/bit_depth.html

Also,  Krita docs says about 16 bit per ch integer vs 32bit per channel fp
without values over 1.0f

====

16bit per channel

One step up from 8bit, 16bit per channel allows for colors that can’t be
displayed by the screen. However, due to this, you are more likely to have
smoother gradients. Sometimes known as “Deep Color”. This color depth type
doesn’t have negative values possible, so it is 16bit precision, meaning
that you have 65536 values per channel.
=====

32bit float

Similar to 16bit float but with even higher precision. The native color
depth of OpenColor IO, and thus faster than 16bit float in HDR images, if
not heavier. Because of the nature of floating point type variables, 32bit
float is roughly equal to 23-24 bits of precision per channel (16777216
values per channel in the 0-1 range), but with a much wider range (it can
go far above 1), necessary for HDR/Scene-referred values. It is also known
as ‘single floating point’.

====


so I guess this mean even WITHOUT going above 1.0 fp output format still
more accurate than 16bit per channel integer tiff or png. But I am bad at
math for PROVING it. :(
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