InterpolationMode is useful when you resize, scale, or rotate the Image with PhotoController. This property is used to specify the quality of resized image.

The best way to describe it is to show some examples.

The following figure is the famous Casino building in Niagara. The original size is 1704X2272, which is not included, since the file size is too large. I will show the resized images with different InterpolationMode setting.

PS. All the jpeg are saved by using quality = 75

InterpolationMode.Default

File Size: 9.7 KB

we can see the image is jagged, very unclear

InterpolationMode.Low

File Size: 9.7KB

The file size is the same, but we can see the image is worse.

InterpolationMode.HighQualityBilinear

File Size: 7.5KB

This time the file size is the best, and the image is not jagged any more, but it is a little blur

InterpolationMode.HighQualityBicubic

File Size: 8.4KB

The file size is increased a little bit, but the image is the best.

New Added Topic: How to fix the resized picture dithering problem?

In the versions before 1.3, when you reduce a large image size, you might see a slim black border line on the image. The reason you see this is doing the resize will dither the image a little bit so that you can see the background at some point.

Hence, you will need the following properties:

PixelOffsetMode
CompositingQuality

Assign some high quality values to these two properties, you can get a perfect resized image afterwards.