[Cin] Fwd: [heroineworshiper/hvirtual] question about clipping in Histogram plugin (Issue #8)

Andrew Randrianasulu randrianasulu at gmail.com
Fri Nov 10 19:27:07 CET 2023

well, Andrea, can I copy your email to GitHub issues or you prefer to
explain it there yourself? I think your use case goes a bit beyond just
testing and into actual workflow category?

---------- Forwarded message ---------
От: Adam Williams <notifications at github.com>
Date: пт, 10 нояб. 2023 г., 21:16
Subject: Re: [heroineworshiper/hvirtual] question about clipping in
Histogram plugin (Issue #8)
To: heroineworshiper/hvirtual <hvirtual at noreply.github.com>
Cc: Andrew Randrianasulu <randrianasulu at gmail.com>, Author <
author at noreply.github.com>

The big problem with histogram is histograms are expected to clamp.  The
graph has to be changed to show a Y range beyond 0-1, you need some more
parameters to define min & max Y.  You could make a new histogram plugin
which implemented the new options.  It gets a bit bloated so the question
is again why you need histogram to support more than 0-1?

Sent: Thursday, November 09, 2023 at 11:14 AM
From: "Andrew Randrianasulu" ***@***.***>
To: "heroineworshiper/hvirtual" ***@***.***>
Cc: "Adam Williams" ***@***.***>, "Comment" ***@***.***>
Subject: Re: [heroineworshiper/hvirtual] question about clipping in
Histogram plugin (Issue #8)

A case of is it worth the effort to support values <0 & >1 & the answer was
no. If you can find a good reason & actually fix everything including the
opengl functions no-one uses, maybe it could work.

well, I looked into playback3d.C and some shaders there surely uses clip?
But biggest problem for me I do not know how to init fp32 fbo/pbo, so it
all remained clipped.

But just switching textures to 32f made big difference with test file
Andrea provided and fade out.


I tried to follow advice given in
(but using more modern GLX_RGBA_FLOAT_BIT_ARB).

use-case is exr/tiff from some photography software or rasterizer, where
values > 1.0f exist. (ffmpeg seems to convert most/all video to integer
formats, but may be in last ffmpeg they added it -
- "avutil/pixfmt.h: add native-endian RGB32F and RGBA32F formats")

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