Rotation for embedded thumbnail

helmut · Post by **helmut** » Mon Oct 10, 2005 4:37 pm

Currently, XnView 1.80 can perform lossless JPG transformations. When transforming, the embedded thumbnail is rotated, too.

It may happen that the rotation of image and embedded thumbnail mismatch for some reason. Currently, there is no way in XnView to make them match, again.

XnView should allow for correcting the mismatch, e.g.

A.) Rotation target
XnView could allow for rotating image & thumbnail seperately. In a drop down list the user could choose the 'Rotation target':
- Image and embedded thumbnail
- Image
- Embedded thumbnail

B.) Recalculate thumbnail
The embedded thumbnail could be always recalculated when a transformation is performed, this would make sure that the embedded thumbnail always matches the image.
When correcting the rotation of the embedded thumbnail, it should be considered that the image might be rotated properly, but the thumbnail isn't. This will mean that the user does not perform a transformation of the image, but the thumbnail must be corrected nevertheless.

I think the user should not have to fiddle around with thumbnail orientation and strongly favour B.) for this reason. The dialog "JPG lossless transformations" dialog could be enhanced with a checkbox "Embed thumbnail". If unchecked, the thumbnail would be removed, if checked the thumbnail will be updated, regardless of whether an transformation (Rotate, Flip) is performed.

Hacker · Post by **Hacker** » Mon Oct 10, 2005 10:05 pm

I would personally prefer A), with B) as an option "recreate thumbnail from image" or so. It might not be quite logical, but I have this quirk of touching the original data as little as possible, thus not changing the thumbnail data (lossless rotation is ok) if possible.

Roman

Olivier_G · Post by **Olivier_G** » Mon Oct 10, 2005 10:57 pm

Hacker wrote:...but I have this quirk of touching the original data as little as possible

Quite true... this is why one should never erase an original file or alter it in any way (I do edit IPTC, though).
But this is about the original file. There is not much to do about an edited/modified version, and the embedded thumbnail becomes quite unimportant then...

Therefore, I believe:
- people who care about integrity and preserving the original will handle this appropriately
- no one would accept a discrepancy between the thumbnail shown (whatever the setting) and the actual image, even if they don't understand how it works

I consider B to be the best (and only?) solution...

Olivier

Hacker · Post by **Hacker** » Tue Oct 11, 2005 9:40 pm

Olivier_G wrote:
Hacker wrote:...but I have this quirk of touching the original data as little as possible
Quite true... this is why one should never erase an original file or alter it in any way (I do edit IPTC, though).

I actually consider losslessly rotated images as "original".

So I vote for lossless rotation, and thumbnail recreating as an option.

Roman

PictureThis · Post by **PictureThis** » Sun Oct 23, 2005 11:30 am

Well, I've been browsing this forum on the subject of rotation. Interesting read. I vote for option B. Thumbnail should represent/follow the real picture at all times. I've seen too many slideshows on LCD/TV with misoriented pictures mainly because of misunderstood behaviour of the picturecollection.

I think a lot of the issues involving rotation could be avoided when lossless
transformation (to correct orientation) is applied at the key moment of acquiring the images from camera/memory card. Not every application is capable of doing this but it seems such a trivial but necessary operation.

Thanks for XnView!

Dreamer · Post by **Dreamer** » Wed Jan 18, 2006 12:42 am

A.) Rotation target
XnView could allow for rotating image & thumbnail seperately. In a drop down list the user could choose the 'Rotation target':
- Image and embedded thumbnail
- Image
- Embedded thumbnail

I support this request. I have few images rotated correctly, with incorrect embedded thumbnail.

Post by **xnview** » Wed Jan 18, 2006 4:35 am

Dreamer wrote:
A.) Rotation target
XnView could allow for rotating image & thumbnail seperately. In a drop down list the user could choose the 'Rotation target':
- Image and embedded thumbnail
- Image
- Embedded thumbnail
I support this request. I have few images rotated correctly, with incorrect embedded thumbnail.

Perhaps i can check orientation of picture to rotate correctly the embedded thumb??

Dreamer · Post by **Dreamer** » Wed Jan 18, 2006 10:11 pm

xnview wrote:
Dreamer wrote:
A.) Rotation target
XnView could allow for rotating image & thumbnail seperately. In a drop down list the user could choose the 'Rotation target':
- Image and embedded thumbnail
- Image
- Embedded thumbnail
I support this request. I have few images rotated correctly, with incorrect embedded thumbnail.
Perhaps i can check orientation of picture to rotate correctly the embedded thumb??

Yes, please check this topic with few suggestions - Lossless rotate for Batch convert.

But we still need this to fix wrong embedded thumbnails.

helmut · Post by **helmut** » Thu Jun 15, 2006 9:50 am

I think that this matter is very important. Rotation is one situation that may cause mismatch of JPG image and embedded thumbnail. When applying any image manipulation the embedded thumbnail must be updated.
Without keeping the embedded thumbnail up-to-date it's useless that the XnView browser shows the embedded thumbnail. Showing a wrong thumbnail with high performance is useless and anyone will have to turn the option "Use embedded thumbnail" off. (I've done this yesterday.)