XnView Software

Posted: **Wed Jul 05, 2006 7:19 pm**

I always used Shift+R to rotate a pic. Today I found another, jpeg losseless rotation with Ctrl+Shift+R. But why not to use this loseless rotation by Shift+R too? This will decrease count of entites in the program.

There is another issue about loseless jpeg: when I'm doing it, xnview tells me it gonna 'remove unused pixels) if its dimension is not a multiple of 8 pixels. But why to ask if the image IS a multiple of 8?

Thanks for the prog between

Posted: **Thu Jul 06, 2006 7:40 am**

Looked at it, and it seems that normal rotation applies to all kinds of formats, while the lossless rotation is a JPG feature and only applies to JPG-images.

Posted: **Fri Jul 07, 2006 12:21 am**

But...

If it is a jpg file, shouldn't the default rotation always be lossless? A warning about losing pixels and an opportunity to use "lossy" rotation is good, but I personally would never ever use "lossy" rotation.

So, my own preferred rotation logic for a single rotation command would be:

Code: Select all

If image is jpeg then 
   Evaluate jpeg lossless rotation
   If jpeg lossless rotation causes lost pixels then
      Explain and prompt user to choose lossless or lossy, etc.
      Perform user choice
   Else
      Perform jpeg lossless rotation
Else
   Perform "standard" rotation

There could be an INI setting to "always perform lossless jpeg rotation" which would suppress the user prompt...

I think this is better for the casual unsophisticated user in order to protect the quality of the jpeg. Most users I know have no clue that jpeg is a lossy format or even what "lossy" or "lossless" mean.

Posted: **Fri Jul 07, 2006 11:23 pm**

I agree with JohnFredC's algorithm.
I, personally, have discovered that loseless rotation in menu Tools about several months after started to use xnview :^)

Posted: **Sat Jul 08, 2006 12:11 pm**

Ok, right

Posted: **Sun Jul 26, 2009 8:49 am**

I agree with zencd's and JohnFredC's suggestion.

The rotation icons are still not the same as the "JPEG lossless transformation" => Rotate (a toolbar icon I discovered today

), and I get the notification about 8-multiple trimming even for images with the proper dimensions that would need no trimming.

XnView Software

Let use jpeg loseless rotate every time it is possible

Let use jpeg loseless rotate every time it is possible

Re: Let use jpeg loseless rotate every time it is possible