I am trying to create a high quality thumbnail of this image, with Java and Scalr 3.2
This is the relevant source code, where THUMB_WIDTH = 77
and THUMB_HEIGHT = 57
BufferedImage srcImg = ImageIO.read(new File(sourceFile));
BufferedImage dstImg = Scalr.resize(srcImg, Scalr.Method.QUALITY,
THUMB_WIDTH, THUMB_HEIGHT);
ImageIO.write(dstImg, format, new File(destFile));
If I use format = "png"
, here is the result:
If I use format = "jpg"
, here is the result:
With imagemagick identify I've found out that the JPEG is saved with a quality of 75 that is totally insufficient to create a good looking thumbnail. The PNG doesn't look good either to me.
Here is the output of identify of the original file and the two thumbnails:
$ identify 42486_1.jpg 42486_s1.jpg 42486_s1.png
42486_1.jpg JPEG 580x435 580x435+0+0 8-bit DirectClass 50.6KB 0.000u 0:00.000
42486_s1.jpg[1] JPEG 77x58 77x58+0+0 8-bit DirectClass 2.22KB 0.000u 0:00.000
42486_s1.png[2] PNG 77x58 77x58+0+0 8-bit DirectClass 12.2KB 0.000u 0:00.000
UPDATE: With a web search I found an article about how to adjust JPEG image compression quality. I wrote my own method to save a BufferedImage setting the quality:
/**
* Write a JPEG file setting the compression quality.
*
* @param image
* a BufferedImage to be saved
* @param destFile
* destination file (absolute or relative path)
* @param quality
* a float between 0 and 1, where 1 means uncompressed.
* @throws IOException
* in case of problems writing the file
*/
private void writeJpeg(BufferedImage image, String destFile, float quality)
throws IOException {
ImageWriter writer = null;
FileImageOutputStream output = null;
try {
writer = ImageIO.getImageWritersByFormatName("jpeg").next();
ImageWriteParam param = writer.getDefaultWriteParam();
param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
param.setCompressionQuality(quality);
output = new FileImageOutputStream(new File(destFile));
writer.setOutput(output);
IIOImage iioImage = new IIOImage(image, null, null);
writer.write(null, iioImage, param);
} catch (IOException ex) {
throw ex;
} finally {
if (writer != null) writer.dispose();
if (output != null) output.close();
}
}
Here are the results. PNG:
JPEG quality 75:
JPEG quality 90 (the gravatars on stackoverflow are saved as JPEG quality 90):
and the filesize:
thumb90.jpg JPEG 77x58 77x58+0+0 8-bit DirectClass 6.89KB 0.000u 0:00.000
UPDATE 2: test to compare Scalr with java-image-scaling.
private void scaleAndSaveImageWithScalr(String sourceFile, String destFile, int width, int height)
throws IOException {
BufferedImage sourceImage = ImageIO.read(new File(sourceFile));
BufferedImage destImage = Scalr.resize(sourceImage, Scalr.Method.QUALITY, width, height);
writeJpeg(destImage, destFile, JPEG_QUALITY);
}
private void scaleAndSaveImageWithJImage(String sourceFile, String destFile, int width, int height)
throws IOException {
BufferedImage sourceImage = ImageIO.read(new File(sourceFile));
ResampleOp resampleOp = new ResampleOp(width, height);
resampleOp.setFilter(ResampleFilters.getLanczos3Filter());
resampleOp.setUnsharpenMask(AdvancedResizeOp.UnsharpenMask.Normal);
BufferedImage destImage = resampleOp.filter(sourceImage, null);
writeJpeg(destImage, destFile, JPEG_QUALITY);
}
JPEG quality 90 generated with Scalr:
JPEG quality 90 generated with java-image-scaling:
I didn't receive any further feedback, so my personal conclusion is that java-image-scaling provides superior quality, and so it's the library that I choose.
@Stivlo, I am sorry for not replying to this, I never got any notification from SO about the question.
java-image-scaling does have some nice filters to help with fine-tuning if you need it. That said, in v4.2 of imgscalr I added the new ULTRA_QUALITY that might get you closer to what you want.
I hope that helps, but realize this is being replied to almost a year after the fact unfortunately. Sorry about that.