filtering (moire / banding(?)) problem when downsizing video #112923

New Issue

Closed

opened 2023-09-26 22:28:37 +02:00 by shaqualeek · 8 comments

shaqualeek commented

2023-09-26 22:28:37 +02:00

https://blender.stackexchange.com/questions/300394/filtering-moire-banding-problem-when-downsizing-video/301814#301814

https://blend-exchange.com/embedImage.png?bid=9sBp9EMy

you might need to unpack the files first and relink them, since blender does not support packing VSE strips. thank you for your time

https://blender.stackexchange.com/questions/300394/filtering-moire-banding-problem-when-downsizing-video/301814#301814 ![image](/attachments/4b751105-535d-4de1-9d1d-88517d921e31) https://blend-exchange.com/embedImage.png?bid=9sBp9EMy you might need to unpack the files first and relink them, since blender does not support packing VSE strips. thank you for your time

tst_scale.blend

16 MiB

688 KiB

shaqualeek added the

labels 2023-09-26 22:28:38 +02:00

Richard Antalik commented

2023-09-27 03:42:30 +02:00

Member

I assume you packed images/movies in VSE, but these do not support packing. Can you upload these separately?

I assume you packed images/movies in VSE, but these do not support packing. Can you upload these separately?

Richard Antalik added

Needs Information from User

and removed

labels 2023-09-27 03:42:38 +02:00

shaqualeek commented

2023-09-27 08:17:25 +02:00

Author

images are packed within the file as 'references'

images are packed within the file as 'references'

Richard Antalik commented

2023-09-29 04:22:16 +02:00

Member

Thanks for info.
Since image is scaled down exactly by half, so I am not sure if bilinear interpolation is doing any work, will have to check though. Technically it should sample 4 neighboring pixels still, but this may be optimized out.

Thanks for info. Since image is scaled down exactly by half, so I am not sure if bilinear interpolation is doing any work, will have to check though. Technically it should sample 4 neighboring pixels still, but this may be optimized out.

Richard Antalik added

Needs Info from Developers

and removed

Needs Information from User

labels 2023-09-29 04:22:28 +02:00

Richard Antalik added the

Video Sequencer

label 2023-09-29 04:37:43 +02:00

Iliya Katushenock added the

label 2023-09-29 08:53:54 +02:00

Richard Antalik commented

2023-10-17 01:29:14 +02:00

Member

I have checked the code, and it indeed works as intended. With 0.5x scale each pixel of smaller image falls perfectly to pixel of large image, so there is no interpolation done effectively.

It is possilbe, that other editors do aditional processing or force different filtering, I can only speculate, but this is not done in VSE.
As for 3x3 subsampling being not as good still, that is still not aa bug but a good point on something that can be improved.

Just a note, that practically identical result to your reference can be achieved by blurring source image(1.5px radius), scaling down and offsetting image by 0.25px to force interpolation being used. I have checked performance of this method, and it is about 2x faster than 3x3 subsampling. @Jeroen-Bakker Do you think pre-blurring method/option could be added for bilinear downscaling?

I have checked the code, and it indeed works as intended. With 0.5x scale each pixel of smaller image falls perfectly to pixel of large image, so there is no interpolation done effectively. It is possilbe, that other editors do aditional processing or force different filtering, I can only speculate, but this is not done in VSE. As for 3x3 subsampling being not as good still, that is still not aa bug but a good point on something that can be improved. Just a note, that practically identical result to your reference can be achieved by blurring source image(1.5px radius), scaling down and offsetting image by 0.25px to force interpolation being used. I have checked performance of this method, and it is about 2x faster than 3x3 subsampling. @Jeroen-Bakker Do you think pre-blurring method/option could be added for bilinear downscaling?

Jeroen Bakker commented

2023-10-17 12:35:40 +02:00

Member

Doubt that pre-blurring works in all cases as it depends on the amount of scale. Filtering can be improved as for example using EWA filtering when downscaling.

Doubt that pre-blurring works in all cases as it depends on the amount of scale. Filtering can be improved as for example using EWA filtering when downscaling.

Richard Antalik commented

2023-10-18 00:45:06 +02:00

Member

It's true, that it would be practical only to about 0.25x scale. Will read about EWA method seems promissing on first glance.

It's true, that it would be practical only to about 0.25x scale. Will read about EWA method seems promissing on first glance.

Richard Antalik added

and removed

Needs Info from Developers

labels 2023-10-18 00:45:42 +02:00

Aras Pranckevicius commented

2024-01-04 10:21:34 +01:00

Member

Just found out that my (not merged yet) PR #116628 seems to fix this issue.

Before:

After:

Just found out that my (not merged yet) PR #116628 seems to fix this issue. Before: ![blender-before.png](/attachments/37e4a8ac-9f44-49a2-ba43-92104755544d) After: ![blender-after.png](/attachments/f8e30a64-730a-4bf5-8697-0952fc60cfe2)

blender-after.png

104 KiB

blender-before.png

289 KiB

❤️ 1 🚀 1

Aras Pranckevicius referenced this issue

2024-01-04 10:38:51 +01:00

VSE: Fix various "off by half a pixel" issues in image transform #116628

Aras Pranckevicius referenced this issue from a commit

2024-01-08 16:51:50 +01:00

VSE: Fix various "off by half a pixel" issues in image transform

Aras Pranckevicius commented

2024-01-08 16:54:45 +01:00

Member

Fixed in 877d9c596a

Fixed in 877d9c596abd3

Aras Pranckevicius closed this issue

2024-01-08 16:54:48 +01:00

Blender Bot added

and removed

labels 2024-01-08 16:54:56 +01:00

Sign in to join this conversation.

No Label

Animation & Rigging

Asset Browser Project Overview

Automated Testing

Blender Asset Bundle

Dependency Graph

Development Management

EEVEE & Viewport

Images & Movies

Motion Tracking

Nodes & Physics

Pipeline, Assets & IO

Platforms, Builds & Tests

Render & Cycles

Render Pipeline

Sculpt, Paint & Texture

Video Sequencer

Virtual Reality

Blender 2.8 Project

Milestone 1: Basic, Local Asset Browser

Good First Issue

Animation & Rigging

Development Management

EEVEE & Viewport

Nodes & Physics

Pipeline, Assets & IO

Platforms, Builds & Tests

Render & Cycles

Sculpt, Paint & Texture

Needs Info from Developers

Needs Information from User

No Milestone

No project

No Assignees

4 Participants

Notifications

Due Date

The due date is invalid or out of range. Please use the format 'yyyy-mm-dd'.

No due date set.

Dependencies

No dependencies set.

Reference: blender/blender#112923

No description provided.