java - 将图像大小调整为固定大小

Question

我需要一个逻辑来重新调整图像大小，使其始终为 320X240 或更小，并且应保持纵横比。

Answer 1

1) determine which side of the image is the larger one
2) if its width, calc: faktor = 320/width, else faktor = 240/height;
3) downscale the image by size.x *faktor, size.y *faktor.

例子：

给定：图像有 1024x640

1) its wider than high.
2) faktor = 320 / 1024 -> 0.3125
3) 1024 * 0.3125 = 320 (huh!)     
   640 * 0.3125 = 200.

Answer 2

看看ImgScalr，Java 库。具有多种转换质量和速度设置，并为您自动缩放。

BufferedImage sourceImage = ImageIO.read(new File(sourceFile));
BufferedImage destImage = Scalr.resize(sourceImage, Scalr.Method.ULTRA_QUALITY, 320, 240, Scalr.OP_ANTIALIAS);