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What resizing/resampling methods are supported by Graphix Mill for .NET? Probably Bicubic and Bilinear, but what about others?
Is it possible to have a method selected automatically by Graphix Mill based on image data or do we need to specify?
Thanks in advance.
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Hello, Graphics Mill supports 14 resampling algorithms, which are defined in InterpolationMode enumeration. You can specify it when call Bitmap.Transforms.Resize method. As supported resampling methods depends on the bitmap pixel format (for example you can not use bicubic one with bitonal image), we have included some pseudo interploations mode in InterpolationMode enumeration: - LowSpeed - Slowest algorithm (as usually it has the highest quality). The same as HighQuality.
- HighQuality - Best quality algorithm (usually lowest speed). When two-pass algorithms are available, Lanczos3Filter is used, for indexed images it is ScaleToGray, and Anisotropic9 for others.
- MediumSpeed - Medium speed algorithm (as usual has medium quality). The same as MediumQuality.
- MediumQuality - Medium quality algorithm (as usual with medium speed). When it is possible, it equals to Bilinear, for indexed images it is ScaleToGray and NearestNeighbour for the rest cases.
- HighSpeed - Fastest algorithm (usually has the lowest quality). The same as LowQuality.
- LowQuality - Lowest quality algorithm (but usually fastest one). It is always the same as NearestNeighbour.
Edited by user Tuesday, January 1, 2008 5:19:09 AM(UTC)
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Best regards,
Fedor Skvortsov
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Thanks, Fedor.
Is there a default setting if we do not set anything specifically? Also, do you support AreaAverage interpolation method, I did not see it on the list.
Thanks again,
-Alex P.
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> Is there a default setting if we do not set anything specifically?
Typically the default value of InterpolationMode property of appropriate transform classes is MediumQuality (i.e. bilinear algorithm if possible).
> Also, do you support AreaAverage interpolation method, I did not see it on the list.
If I understand the term "area average" correctly, this is the same as BoxFilter. But other filter algorithms should produce better result, because they take into account the distance from the center pixel during averaging.
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This is very helpful. Your answer explains why we received poor results with default setting (bilinear).
The obvious quality winner in our tests is Lanczos3Filter interpolation, but it also takes double the time of many other algorithms. Can you recommend another algorithm from your supported list that would be a good combination of quality and speed with maybe a bias towards quality? We would like to use the best quality algorithm to produce larger images (up to 1,000 pixels across) but can sacrifice a little bit of quality for generating 80x80 thumbnails. Any advice?
Thank you again,
-Alex P.
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The best of "fast" algorithms for downsampling is anisotropic interpolation (it is bad for upsampling through - it degenerates to nearest neighbour algorithm when target width/height is larger than original image dimensions).
There are two kinds of anisotropic algorithms available in Graphics Mill - 4-points based and 9-points based. The first one works faster but less precise, the second one - vice versa. Experiment what one is more acceptable to you.
Hope this helps.
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