Also, here is the jpegtran manual for further reference. The rotation is performed counter-clockwise. You can also use your mouse to rotate the image. Remember that 360 degrees is one full rotation, and 3.14 radians ( radians) is 180 degrees. You can rotate an image by specifying degrees or radians. In either case, if you want to rotate 90 degrees counter-clockwise, replace the 90 in either command with 270. This tool rotates images by arbitrary angles. Jpegtran -rotate 90 -trim input.jpg output.jpg To eliminate the border, use the following command instead: If the input image dimensions are not multiples of the JPEG block size, you may notice a small, undesirable border along some portions of the image. Use the following command to rotate input.jpg 90 degrees clockwise and save the result to output.jpg: In reply to Ben, you can use the freely available jpegtran. JPG is a lossy compression image format.Īctually, as it turns out, one can losslessly rotate by multiples of 90 degrees (or transpose) a JPEG file by doing nothing more than rearranging and/or changing signs of the quantized DCT coefficients in each block. Fmw42 wrote:Even if the rotate 90 were lossless, just reading in a jpg and writing it out again would have some losses.

How to rotate a jpeg