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What I'm working on...


itsjustme

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"8 bit images are encoded with a gamma but not in an EXR image"

Does that mean the values are actually changed in the 8 bit mage?

If I render a 50% gray in a TGA and an EXR and load those into a paint program and sample the color values, both will say they are 128, which is 50% gray.

Where is the gamma correction happening?

 

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The gamma correction happens for viewing on a monitor.  An EXR image doesn't store gamma correction because there is nothing to correct...it is a linear image by default.  8bit images are being corrected to be viewed the same.

 

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EDIT

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If you render your 8bit image using the same gamma setting as the EXR image (it is always 1.0 gamma), they shouldn't match.  However, if you render the 8bit image at 2.2 gamma, they should match.

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Here are three renders to compare.  I included the original OpenEXR in the zip (16bit 1.0 gamma), which I then used Black Magic Fusion to convert to 8bit 2.2 gamma (PNG), a render straight to 8bit 2.2 gamma (PNG) and an 8bit render straight to 1.0 gamma (PNG).  The render straight to 8bit 2.2 gamma does match pretty closely the 8bit image converted from a 1.0 gamma OpenEXR, but the 8bit image rendered straight to 1.0 gamma does not.  This is because the 8bit image is being "corrected" as if it were a 2.2 gamma image by your computer/monitor.  The two other PNG's are also being "corrected", but they have the expected gamma curve of an 8bit image while the 1.0 gamma PNG does not.

 

Hope that helps.

1_0_gamma_EXR_converted_to_2_2_gamma.png

2_2_gamma_rendered_at_2_2_gamma.png

2_2_image_rendered_at_1_0_gamma.png

 

Gamma_images_10_01_2019.zip

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  • 3 weeks later...
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It's been a long time since my last post here, but I hope to have more things soon-ish.  I've been updating the Squetch Rig, Squetchy Sam and rigging Bertram.  I'm also planning to rig Donna and make an installation tutorial for the updated rig.  While I was updating Sam's rig, I decided to tweak his looks a little and it gave me an image I can post.  I'm still debating putting a head of hair on him.

 

 

Sam_10_07_2020.png

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  • 6 months later...

Time has gotten away from me...I've got several things in-progress, so I will eventually have a pretty good dump of updates.  The Squetch Rig update is finished, but I want to make the updated installation tutorial before I post it, Bertram has been rigged for quite a while, now I'm working on his texturing...which will probably result in a flattening, decaling and texturing set of tutorials or mini tutorials.  Sam's updates are done, but I decided to leave him with group colors instead of full-blown texturing.  I've also rounded a few script ideas out...hopefully, I'll get some animation done eventually.  Yup, I'm as slow as a glacier.

 

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Okay, I haven't posted anything for quite a while...I've gone down several rabbit holes.  Eventually, I'll post everything.  For now, I have something silly I can post.  It's a test of three doughnuts multiplied to fill trays.  For something more than a test I would make several versions so that they didn't look identical...but it's something I can show.

 

 

doughnut_test_10_15_2022.png

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I posted what I think is the final for the lighting and texturing of the Exam Room here.  I thought it would go quicker than it did, but a couple of weeks has been quick compared to how slow I've been working for a long time.  Next, I'll try to finish up Bertram's underwear and socks.

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