Author Topic: Low quality on my shadows (shadow quality = 5)  (Read 1647 times)

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Offline mattjgerard

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Re: Low quality on my shadows (shadow quality = 5)
« Reply #15 on: August 07, 2018, 12:34:57 pm »
Is the gradient banding in the shadows visible before changing down from 32 bit mode? Perhaps try first switching to 16 bit mode and adding a bit of noise to the background before downing to 8 bit. Does that help with the banding? What about saving the final image out as a better format than JPEG, such as a lossless TIFF or PNG? If you attach the KSP to your post I'll take a look as well.

Cheers,
Eric

This is hugely common in the world I came from, the video motion graphics animation world. For a long time these slight gradients were the rage for animation backgrounds which was hell for encoding anything worth posting on the web. There was a balance of the percentage difference between the light/dark of the gradient vs the pixel distance the gradient was applied over. If the ratio was too low (80% grey to 90% grey over 1080 pixels for example) you would get banding with certain compression schemes, depending on how far you had to go with the bit rate.

So, in the still world, this translates to image compression (jpeg vs PNG vs uncompressed like TIFF or photoshop) You can certainly render out 32 bit images, but if you have a less than stellar display, the conversion to 8 bit on the way to the monitor and the monitors gamut will make that banding appear when it really isn't in the image data. Then, if you save it out as a compressed jpeg or something else, that compression will further degrade the gradients and worsen the banding.

Solutions to this in my experience is as follows-

1) What Eric mentioned, add some noise to the gradient. You are tricking the encoder to give that area more bandwidth by making the gradient imperceptibly uneven. Encoders look for similar pixels, then link them and treat them the same (oversimplified, but the idea works) Only once the pixels go beyond the threshold of being "different" from their neighbors will the encoded unlink them and give them their own data. By adding noise, you are making each pixel just different enough to trick the encoder to treat them individually.

2) Increase the contrast of the light vs dark areas of the gradient. since the shadow of your image is very close in tone to the ground it is falling on, the encoder creating the banding as a way of saving data. This can happen in supposedly uncompressed image formats too if the differences are small enough.

If you can try to look at your image on a high end monitor that will process those slight gradients well, that might give you some insight as to if the problem is your monitoring, or if its in the file itself. You can use some of the measurement tools in photoshop too in order to sample pixels across the gradient to see if they are changing smoothly or in obvious steps. I don't know what the final destination of your images are, but I know in my world, I had to focus a lot of my troubleshooting on what would work for the final delivery, be it DVD (green gradients suck) youtube (everything sucks) Vimeo (re-encoded everything no matter what) or streaming.

Offline zooropa

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Re: Low quality on my shadows (shadow quality = 5)
« Reply #16 on: August 08, 2018, 02:01:40 am »
Thanks so much for your detailed explanation. I think the point two that you are indicating might be the problem (the one pointing the similarities between the color of my shadow and the color of my background).

Regarding the gradient you name a few times I imagine you mean the "gradient" that the lights does in itself while projecting? I did not apply any gradient.

My renders are just for my personal web : ) thanks a lot for that much insights.

Offline zooropa

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Re: Low quality on my shadows (shadow quality = 5)
« Reply #17 on: August 08, 2018, 02:02:09 am »
My bad, plane under my object did not solve my shadow problem....:(

No problem.
Just

mwodarz@inneo.com
(Currently you’ll receive an “out of office reply”)



Sent it! Thanks : )

Offline mattjgerard

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Re: Low quality on my shadows (shadow quality = 5)
« Reply #18 on: August 08, 2018, 06:39:29 am »
Thanks so much for your detailed explanation. I think the point two that you are indicating might be the problem (the one pointing the similarities between the color of my shadow and the color of my background).

Regarding the gradient you name a few times I imagine you mean the "gradient" that the lights does in itself while projecting? I did not apply any gradient.

My renders are just for my personal web : ) thanks a lot for that much insights.

Yes, the gradient that is caused by the lighting, not any gradient that you have applied, correct.

Offline zooropa

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Re: Low quality on my shadows (shadow quality = 5)
« Reply #19 on: August 09, 2018, 04:15:23 am »
Thanks so much for your detailed explanation. I think the point two that you are indicating might be the problem (the one pointing the similarities between the color of my shadow and the color of my background).

Regarding the gradient you name a few times I imagine you mean the "gradient" that the lights does in itself while projecting? I did not apply any gradient.

My renders are just for my personal web : ) thanks a lot for that much insights.

Yes, the gradient that is caused by the lighting, not any gradient that you have applied, correct.

I am making a test now with a lighter background...I think the biggest outcome, personally, from this topic its your insights about the ratio between the shadow/background levels. Really appreciate this !