Jpegtrans with

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Nick

Jpegtrans with

Post by Nick » Wed Jun 20, 2007 10:12 am

Hi,

I use: nconvert -v -keepfiledate -jpegtrans exif *.jpg
to convert my holiday pictures without (!!) loss.

My question is: The only purpose is to rotate losslessly according to exif-information. Do I need anymore parameters to leave everything else unchanged, like:
-keepdocsize : Resize bitmap function of the old and new DPI value
-keepcspace : Keep original color space if possible
-ratio : Keep the ratio for scaling

Or anything else? So, does jpegtrans automatically keep the color space, ratio and keepdocsize (the last one I do not understand).

I need to be sure!! Don't want to discover in 5 years that I lost information which I cannot recover.

Thank you very much!
Nico

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xnview
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Re: Jpegtrans with

Post by xnview » Wed Jun 20, 2007 2:28 pm

Nick wrote:Hi,

I use: nconvert -v -keepfiledate -jpegtrans exif *.jpg
to convert my holiday pictures without (!!) loss.

My question is: The only purpose is to rotate losslessly according to exif-information. Do I need anymore parameters to leave everything else unchanged, like:
-keepdocsize : Resize bitmap function of the old and new DPI value
-keepcspace : Keep original color space if possible
-ratio : Keep the ratio for scaling

Or anything else? So, does jpegtrans automatically keep the color space, ratio and keepdocsize (the last one I do not understand).

I need to be sure!! Don't want to discover in 5 years that I lost information which I cannot recover.

Thank you very much!
Nico
No need to other parameters, but as i said often :-) it's better to try on a copy folder first...
Pierre.

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Re: Jpegtrans with

Post by Guest » Thu Jun 21, 2007 2:21 pm

xnview wrote: No need to other parameters, but as i said often :-) it's better to try on a copy folder first...
I am slightly confused, because also the pictures that are already horizontal (no need for rotating, EXIF says horizontal is okay) seem to be rotated !!

Their file size definetely slightly decreases.

I've tried it manually with xnview, and automatically rotated pictures end up with the file size which I get after rotating the (correct) original 4 times.

Note: The pix is dividable by 4 in both height and width!

Thanks for a short answer!!

Best regards,
Nico

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xnview
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Posts: 33647
Joined: Mon Oct 13, 2003 7:31 am
Location: France
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Re: Jpegtrans with

Post by xnview » Thu Jun 21, 2007 3:40 pm

Anonymous wrote:
xnview wrote: No need to other parameters, but as i said often :-) it's better to try on a copy folder first...
I am slightly confused, because also the pictures that are already horizontal (no need for rotating, EXIF says horizontal is okay) seem to be rotated !!

Their file size definetely slightly decreases.

I've tried it manually with xnview, and automatically rotated pictures end up with the file size which I get after rotating the (correct) original 4 times.

Note: The pix is dividable by 4 in both height and width!

Thanks for a short answer!!

Best regards,
Nico
Could you send me a sample, please?
Pierre.

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