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Ross Buggins  
#1 Posted : Saturday, June 21, 2008 8:34:19 PM(UTC)
Ross Buggins

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Hi,

I'm using the image uploader on a project and I have this question from a developer on the team:

How does the subsampling in the image uploader work?
Can it do no-integer rate reductions and does it use a subsampling filter?

Regards,

Ross Buggins
Eugene Kosmin  
#2 Posted : Sunday, June 22, 2008 1:27:48 PM(UTC)
Eugene Kosmin

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Hi,

2x2 chroma subsampling is used.

Quote:
Can it do no-integer rate reductions and does it use a subsampling filter?

Could you specify your question more detailed?
Best regards,
Eugene Kosmin.
Aurigma Development Team
JHealy  
#3 Posted : Thursday, June 26, 2008 12:35:15 AM(UTC)
JHealy

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Joined: 1/16/2008(UTC)
Posts: 8

As a further to the initial post I also have a question about this,

The images I get from the uploader are then used in image processing algorithms. To cut down on upload times the thumbnail for the image is uploaded reduced to about 800X1000, my question is what sampling is used to reduce the image size from original to smaller? Do you use integer sub sampling or an actual sub sampling filter? If you use a filter what filtering method do you use? If you don’t use a filtering method how do you deal with the aliasing that integer sub sampling will introduce?

Also what are the differences between the flags for uploadThumbnailResizeQuality? Does this take any additional filtering into account?

And one final question, can the uploader convert input files into gray scale and send these?

Many thanks for your help,

Regards,

J Healy
Eugene Kosmin  
#4 Posted : Thursday, June 26, 2008 12:25:28 PM(UTC)
Eugene Kosmin

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Hello,

We don't use integer sampling (or so called nearest neighbour algorithm) - it produces awesome aliasing effects. When you set medium quality of resize -anisotropic interpolation is used. And so called "Bell filter" is used for high quality resampling.

Quote:
And one final question, can the uploader convert input files into gray scale and send these?


No, unfortunately Image Uploader doesn't provide such funtionality.

Edited by user Thursday, June 26, 2008 1:43:03 PM(UTC)  | Reason: Not specified

Best regards,
Eugene Kosmin.
Aurigma Development Team
JHealy  
#5 Posted : Saturday, June 28, 2008 5:35:50 AM(UTC)
JHealy

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Joined: 1/16/2008(UTC)
Posts: 8

Many thanks for your answers Eugene,

Regards,

J Healy
Eugene Kosmin  
#6 Posted : Sunday, June 29, 2008 4:07:50 PM(UTC)
Eugene Kosmin

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Posts: 455

Was thanked: 27 time(s) in 27 post(s)
You are welcome.
Best regards,
Eugene Kosmin.
Aurigma Development Team
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