PNG export 8 bit vs 16 bit question

Flame Flame Questions
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1

When I export out a 16 bit rec709 or srgb png - in preview (mac) or image viewer (linux) the file will look like a linearized file and appear very bright. The file looks fine in flame, nuke, resolve and I know its correct, but unfortunately for producers this does not work since they like to check in preview. If i export 8 bit PNG its fine.

is there a way to do export 16 bit rec709 PNG from flame and have it not do this? i have tired from desktop, from batch via write file + various tagging methods on export to try and force it, but haven’t been able to find anything that works.

Again 8 bit export displays as expected, just 16 bit does not.

I tried on flame 2025 mac and 2024.1.2 linux and got the same results.

here is what i see on get info from mac preview for each.

Screenshot 2024-11-11 at 17.01.18
Screenshot 2024-11-11 at 17.01.18618Ă—200 8.9 KB

Screenshot 2024-11-11 at 17.00.59
Screenshot 2024-11-11 at 17.00.59796Ă—184 8.18 KB

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I think you can export the 16b with a colour transform and use the LUT remove_2.2_gamma, and it should match the 8b. I don’t know why. That’s an @finnjaeger question.
Of course, that might screw it up for everything else, but it will look right in preview.

3

hmm thats funny, i would actually mark this as a bug to flame support - seems to me that flame just tags 16bit pngs as linear in the exif data , i never use png so i have never noticed this.

exporting 16b png from nuke gets me sRGB color profile as expected

you can at least change it using → tools-> assign profile in macOS preview

2 Likes
4

I tried changing it in assign profile and it made no difference.

5

you need to close preview and open the image again to have it reload using the new profile

can look at some way later to change it with a script or something need to where it sits in exif

6

because producers and clients feel super comfortable doing that. hahahha.

thanks for investigating. I’ll flag as a bug as it really should not require any reworking / tagging ultimately.

7

funny enough, it does something but now what we want, let me digg deeper…

8 
General
Complete name                            : /Users/finn/Movies/16bpngfromflame.00864207.png
Format                                   : PNG
Format/Info                              : Portable Network Graphic
File size                                : 11.9 MiB

Image
Format                                   : PNG
Format/Info                              : Portable Network Graphic
Compression                              : Deflate
Format settings                          : Linear
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Color space                              : RGB
Bit depth                                : 16 bits
Compression mode                         : Lossless
Stream size                              : 11.9 MiB (100%)
Gamma                                    : 1.000

vs from nuke (correct)

General
Complete name                            : /Users/finn/Movies/16bpngfromnuke.png
Format                                   : PNG
Format/Info                              : Portable Network Graphic
File size                                : 4.49 MiB

Image
Format                                   : PNG
Format/Info                              : Portable Network Graphic
Compression                              : Deflate
Format settings                          : Linear
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Color space                              : RGB
Bit depth                                : 16 bits
Compression mode                         : Lossless
Stream size                              : 4.49 MiB (100%)

seems like that added “gamma” tag is the issue. Also note that the nuke exported PNG is half the size… thats odd. maybe tell adsk that this additional gamma metadata is the problem, then it should be rather easy for them to fix

9

just run this it will remove that gamma metadata which is bs.

brew install exiftool or probably yum install exitftool (caution as always when installign random tools, but exiftool ist pretty popular…

exiftool -overwrite_original -Gamma= filename.png

works fine

1 Like
10

got one more, here is a python script

run it with. python3 path/to/script/fixpngmetadata.py it will launch a filebrowser, you can select a folder containing many pngs, it will go over each png and remove the gamma metadata using exiftool

hope this helps, but yea ideally adsk fixes this, i dont know any case where you would want this … at least give us a button :stuck_out_tongue:

fixpngmetadata.py (918 Bytes)
idk how to write these for flame but this could be a easy right click action in mediahub maybe …

3 Likes
11

converted for flame(mediaHub), but i could only get it to work using the folder path instead of the filepath:
fix_png_metadata.py (2.3 KB)

3 Likes
12

legend