Color Correction Map - artifacts with HDR images

#1

This is with max 2012/64b

I’m getting black pixel artifacts when using a HDR image with the built in Color Correction map. There are black spots/pixels that tend to appear in image areas where RGB value is greater than 1.

I remember reading here that Color Correction doesn’t handle HDR images correctly but I can’t find the thread.

I’m looking mainly for a way to manipulate gamma and contrast values of HDRIs. Cuneyt Ozdas’ ColorCorrect was my weapon of choice for earlier versions of max, unfortunately the max 2012 recompile seems to have issues so I need to find a working alternative.

#2

Yeah, i’m using 3dsMax 2011 and i have some issues with the Color Correction map using HDRI´s and .EXR´s in 32bit float. Sometimes using the output options for the map give me better results, if not then i have to adjust in Photoshop directly.

#3

I remember max 2010 and below the ColorCorrection map didn’t work with floating point images at all, although that was resolved in 2011. Not surprised it’s still got floating point issues though. What issues exist with the 2012 ColorCorrect map?

  • Neil
#4

hi

yes colorcorrection and 32Bit Floating Images don´t work, 2012 too. But you can use for colorcorrection, brightness and contrast, the RGB-Curve of your Bitmap Shader. Got to Output and set the RGB-Curve. That work at 3dsmax 1.0 smile

if you need 100% Alpha of your Backgound images, use the Environment/Background Camera Map.

mfg
hot chip

#5

What exactly are you doing with the CC map? Can you post a scene and map showing exactly what you are seeing? I have seen maps clamped by CC, but never black artifacts. Also, how are you using them? What renderer? Are you rendering to float with that renderer?

-Eric

#6

Here’s a comparison between the plain HDR map and the same map used in a Color Correction node:

Meanwhile I found out what’s causing this, it happens when you disable bitmap filtering. Still, the artifacts appear only in the Color Correction node, the sole map and its output are fine with filtering disabled.

So at least I know what’s causing it.

FYI, it’s not clamped, so 32 float works just fine here.

Neil, as for Cuneyt’s ColorCorrect in max 2012, this is what I get almost every time I use it:

It’ll either hang max or crash it (actually it crashed 2 seconds after making this screenshot) so I’d rather not use it in production before it has been fixed.

Thorsten, using the map output curve is (at least for me) like trying to assembly a swiss watch with gloves, and that’s probably why it was sufficient back then in max 1.0
Trying to reproduce certain low/mid/high values with the curve alone is (almost) impossible, that’s why I’d rather have a numeric tool.

Eric, just to answer your questions: I’m using Brazil, but since bitmap filtering is handled by max itself I assume this issue applies regardless of the renderer used.

I’d be happy to know if anyone can reproduce this or if it’s something to do with my HDR image (unlikely but possible). If others can actually reproduce this I’m going to submit a defect report.

#7

aha thanks pokoy for the info´s.

#8

Does it actually render with the artifacts, or are you seeing them in the editor? What if you disable map filtering in the Brazil Render Parameters? What if you set the bitmap blur to 0.01 instead of NONE?

Just a few other things to investigate,
-Eric

#9

Yes, it renders with those black pixels/spots, either it’s used as an environment map, mapped on geometry or previewed in the material editor.
This happens with every render engine I guess, so far I’ve tested it with Brazil, scanline, mray and iray, always the same.

I just converted the HDR to EXR and it’s having the same issues, though the black pixels appear in slightly different places.

Using bitmap filtering solves it, yes, it only happens when it’s set to ‘none’.
I still think it’s probably a bug since it happens only when the hdr/exr image is used in a Color Correction map.

I’d be happy if someone could try to recreate it, just to make sure I’m not making wrong assumptions.

#10

ColorCorrect crash issue should be fixed now with v3.4.105. Please test.

http://www.cuneytozdas.com/software/3dsmax/#ColorCorrect

#11

Thank you x 1000! Just tested, seems to work without problems :bowdown:
I couldn’t live without your map, it’s really the only way to go if one needs full control over colors and levels.

This solves my original problem as well as ColorCorrect handles HDR images correctly.

#12

Thanks Cuneyt for getting that fixed, no one should be forced to use the builtin color correct map :slight_smile:

  • Neil
#13

That applies to renderers as well :wink:

#14

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