NeitzelLib/core/docs/image-fitting.md

Opaque image fitting

ImageScaler.fitOpaque(source, maxWidth, maxHeight, background) returns an independent RGB BufferedImage. It fits within positive bounds without enlargement, keeps aspect ratio to the nearest pixel (minimum one pixel per dimension), and composites transparent pixels onto the supplied opaque AWT Color. Bilinear interpolation is used. The source is unchanged and graphics resources are released.

This operation is independent of file format and wire encoding. Callers own image decoding, any source subsampling, and target quantization. Existing PNG scaling methods retain their original behavior.

ImageScalerTest verifies fitting, no enlargement, transparent/partial-alpha composition, narrow images, source preservation, and invalid bounds.