[BUG] VapourSynth Levels filter does not work for RGB24 image streams

[BUG] VapourSynth Levels filter does not work for RGB24 image streams - Printable Version

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+--- Thread: [BUG] VapourSynth Levels filter does not work for RGB24 image streams (/thread-1564.html)

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RE: VapourSynth Levels filter does not work for RGB24 image streams - Selur - 17.10.2020

I'm not totally sure atm. how to handle 32bit Tiff with Levels properly.

Load a single 32bit TIFF with vsImageReader and applying levels on it returns a black screen the way I assumed it would work.
I assumed that the color space should be RGBS with 32bit precision and thus analog to limiting to 16-235 I used min_in = 16 << (32-8), max_in=235 << (32-8), min_out= 16 << (32-8), max_out = 235 << (32-8).
That gave me a black preview and I'm not sure whether this is due to a limitation of the preview, if I did something wrong or if it's a limitation somewhere else.
So any help is welcome.

# Imports
import vapoursynth as vs
core = vs.get_core()
# source: 'C:/Users/Selur/Desktop/images v2/TIFF 32-bit.tif'
# current color space: RGBS, bit depth: 32, resolution: 640x480, fps: 25, color matrix: 709, yuv luminance scale: full, scanorder: progressive
# Loading C:\Users\Selur\Desktop\images v2\TIFF 32-bit.tif using vsImageReader
clip = core.imwri.Read(["C:/Users/Selur/Desktop/images v2/TIFF 32-bit.tif"])
clip = core.std.Loop(clip=clip, times=100)
# Input color space is assumed to be RGBS
# making sure frame rate is set to 25
clip = core.std.AssumeFPS(clip, fpsnum=25, fpsden=1)
# Setting color range to PC (full) range.
clip = core.std.SetFrameProp(clip=clip, prop="_ColorRange", intval=0)
# Color Adjustment 
clip = core.std.Levels(clip=clip, min_in=268435456, max_in=18446744073357230080, min_out=268435456, max_out=18446744073357230080) 
# Output
clip.set_output()

-> posted over at doom9s (https://forum.doom9.org/showpost.php?p=1925989) to see whether someone there knows how to do it properly.

Quote: Not sure why it detects JPEG as YUV444P8@8 and same time other image formats as RGB24@8. Maybe JPEG is somehow special...

Hybrid takes the color space from MediaInfo which reports:

Image
Format                                   : JPEG
Width                                    : 640 pixels
Height                                   : 480 pixels
Color space                              : YUV
Chroma subsampling                       : 4:4:4
Bit depth                                : 8 bits
Compression mode                         : Lossy
Stream size                              : 44.5 KiB (100%)
ColorSpace_ICC                           : RGB

for your 'JPEG 8-bit HQ enabled.jpg' file.
and for the "PNG 8-bit":

Image
Format                                   : PNG
Format/Info                              : Portable Network Graphic
Format_Compression                       : Deflate
Width                                    : 640 pixels
Height                                   : 480 pixels
Color space                              : RGB
Bit depth                                : 8 bits

Cu Selur

RE: VapourSynth Levels filter does not work for RGB24 image streams - shijan - 17.10.2020

As i remember in Vapoursynth FAQ about a Levels it was a notice that they work very different in 32 bit depth http://www.vapoursynth.com/doc/functions/levels.html

In both PhotoLine and Photoshop image editors there is no option to export 32 bit PNG. So i guess it is something very uncommon.

RE: VapourSynth Levels filter does not work for RGB24 image streams - Selur - 17.10.2020

@The_Tinkerer: send you a link to a new dev version via PM for testing,..
Hoping that this properly handles 32bit images.

Cu Selur