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Resize Algorithm
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The resize algorithm (or resample filter) determines how pixels in a picture are affected when it is resized. Some algorithms add a blurring effect while others maintain the hard edges between different areas of a picture. The algorithm that generally gives the best results is "Lanczos3". However, depending on the nature of your picture, you may get better results (smaller file size or higher image quality) by trying out one of the other algorithms. You can see the result produced by the chosen algorithm by looking at the picture on the "Thumbnail preview" panel. Easy Thumbnails offers a choice of nine resize algorithms, as well as an option for lossless rotation of JPEGs, and an option to automatically choose the best resampling method for the type of picture being processed.
[ Smart ]
This option uses the Mitchell algorithm when processing JPEG images and the Lanczos3 algorithm for other image types. If the Mitchell algorithm is used to reduce the size of an image, a value of +20 sharpening is applied after resizing if the Sharpness slider control is set to 0.
None
The image is simply stretched to the new size. This is the fastest method but produces the least smoothing.
Triangle
This algorithm produces sharp transition lines and is also relatively fast. It produces reasonably good results with a little smoothing for both reduction and magnification.
Hermite
The Hermite method creates noticeable smoothing but maintains a good degree of sharpness. It is relatively fast.
Bell
This algorithm is also relatively fast and produces smooth image, bordering on soft.
B-spline
This method does not produce sharp transitions and may cause excessive blurring. It has the advantage of dampening noise and JPEG artifacts. B-spline is one of the slower algorithms.
Lanczos3
This is the slowest method but it usually produces the sharpest images (comparable to fractal resizing). Under certain conditions, it may introduce some ringing patterns and emphasize JPEG artifacts.
Mitchell
Resizing with this algorithm produces no sharp transitions and tends to be a good compromise between the "ringing" effect of Lanczos and "blurring" of other methods. It is often used with photos in combination with the sharpness option to reduce smoothing. The Mitchell algorithm produces good results when enlarging pictures. It is also one of the slower algorithms.
Nearest
This algorithm is recommended for small icons or lines/outlines. It works best with illustrations containing non-anti-aliased edges.
Linear/Fast Linear
This is a reasonably fast method that does not emphasize jagged edges, but it does tend to blur the image slightly.
Lossless
Technically speaking, this is not a resampling filter. This option is available to produce lossless rotations (90° steps) of JPEG images. The quality of the image is unaltered when a lossless rotation is applied. There might be a slight reduction in size of the resulting image if its dimensions do not match the DCT (Discrete Cosine Transform) block unit. If this option is used on non-JPEG images, it operates like the [Smart] setting.