Is there a Java library for rotating JPEG files (90/180/270 degrees) without quality degraded?
+5
A:
I found this: http://mediachest.sourceforge.net/mediautil/
API: http://mediachest.sourceforge.net/mediautil/javadocs/mediautil/image/jpeg/LLJTran.html
Henry
2009-04-01 17:52:11
very neat, great find!
Alex Beardsley
2009-04-01 19:15:47
A:
Rotation is inherently not reversible with the same fidelity due to rounding off in mapping function. Which means if you keep rotating, the quality will degrade.
Indeera
2009-04-01 17:57:54
Unless you are rotating any multiple of pi/2, which means you are just changing the positions of pixels, but do not need to change their values.
Varkhan
2009-04-01 18:00:12
Yes, that's true. However, I think there would be a compelling argument for it to do so, since it's the most common case... for instance, putting photos taken with the camera upside down, or rotated 90° for format reasons...
Varkhan
2009-04-01 18:13:09
+1
A:
In my opinion, ImageMagick is the premier piece of software to do this in. It's probably a bit of overkill for what you need, but the apis are amazing and you can pretty much do whatever you want to images with it.
Check out JMagick for the Java api.
Greg Noe
2009-04-01 18:34:17
A:
You don't need an external library for this kind of thing, it's all built into SE. The easiest being the rotate() function of the Graphics2D object.
For example:
Image rotatedImage = new BufferedImage(imageToRotate.getHeight(null), imageToRotate.getWidth(null), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = (Graphics2D) rotatedImage.getGraphics();
g2d.rotate(Math.toRadians(90.0));
g2d.drawImage(imageToRotate, 0, -rotatedImage.getWidth(null), null);
g2d.dispose();
no loss!
Or, if you want to be extra careful, just use BufferedImage.getRGB(x,y), and translate it pixel by pixel on to the new image.
J_Y_C
2009-04-01 18:49:31
That wouldn't be lossles, as you'd have to decode and re-encode the image, which will result in loss of data. JPEGs can be losslessly rotate in 90-degree steps, when done correctly.
Joachim Sauer
2009-04-01 18:52:46
This is fine for PNG / GIF I guess, but not lossless to JPEG unfortunately.
Henry
2009-04-01 21:28:39
I don't understand why you would say this isn't lossless? Especially if you are doing this operation pixel by pixel?
J_Y_C
2009-04-02 00:35:27