XnView Software

I assume, that all compression methods for TIFF images allow lossless rotation (ZIP, LZW, JPG, etc). That means that the "Lossless rotation" transformation filter should work for TIFF images. Unfortunately, nothing happens.
Steps to reproduce:

• Select several TIFF images
• Press Ctrl-U (Batch processing)
• Activate "Image -> Lossless rotation" and press "Go" button

Result: The progress bar shows the images are processed, no errors are reported. But no output images are created.
Expected: The output images are created with selected rotation applied.

XnView version: 1.97.3

I think "Lossless" operations are for JPEG files that have lossy compression. The main idea behind this is to apply some transformation without further recoding the file (and thus losing some information because of lossy compression). For a lossless format such as TIFF you can just normally rotate the file and save it afterwards without loss of data.

No this lossless rotation is ONLY for JPEG files

xnview wrote:No this lossless rotation is ONLY for JPEG files

In this case please consider:

• Renaming this transformation filter to "JPEG Lossless rotation". That will be in line with other menu items.
• Showing a message during the transformation that "Given transformation is not applicable for the input format (was TIFF/LZW but expected JPEG)".

It would be very nice, if you can confirm the following: when "normal" rotation is applied and the rotation is for [180, 90, -90] degrees, the algorithm is optimized for these cases ("fast" rotation is performed).

Just one cent:

For TIFF images, the compression types ZIP, LZW, JPG – all support "lossless" rotation. Perhaps I would be good idea to leave this filter, but to apply it also to TIFF images, where is applicable (or report error, where it is not).

When you are using a lossless compression method (e.g. LZW, ZIP), saving the file after a 90º rotation is always a lossless operation.