Counter-Intuitive Behavior of File Size

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XnNewbie
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Counter-Intuitive Behavior of File Size

Post by XnNewbie » Sun Mar 11, 2018 4:44 pm

Dear Board,

being new to the board and XnConvert I did not find an answer to my question; so please forgive me if there is one and re-direct - thank you!

(1)
I need/use XnConvert (Version 1.76 - x64 (Jan 16 2018) - Libformat version 7.16, running on High Sierra 10.13.3) to add various borders to tiff-files which are made for printing at service providers. Tiffs are exported from Capture One Pro (11.0).

While on screen XnConvert seems to do what I need, I am getting nervous when I look into the file sizes after conversion. Eg; when I add 20 pixel of a border to each side of the tiff file, the resulting file will have a smaller size than the original file:

original file: 2303 x 1535 pixel - size 13.996.371 Byte
resulting file: 2349 x 1575 pixel - size 13.892.655 Byte

This seems counter-intuitive to me and makes me wondering what XnConvert possibly does with the original tiff content. The two settings I could identify that will have impact on the resulting file size ("Preserve Metadata", and "Preserve color profile") both are ticked. Is there an easy explanation for this behavior?

(2)
The latter brings up another question (not sure if it makes sense, but I try): which specific "color profile" is meant in that latter option? As there are several that come into play going from a camera raw file to a soft proof (profile of the camera, screen, print paper etc).

Any answer in rather easy terms is highly appreciated - I am not fully IT illiterate, but not an expert or professional either. Thank you!

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XnNewbie

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xnview
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Re: Counter-Intuitive Behavior of File Size

Post by xnview » Mon Mar 12, 2018 10:58 am

XnNewbie wrote: This seems counter-intuitive to me and makes me wondering what XnConvert possibly does with the original tiff content. The two settings I could identify that will have impact on the resulting file size ("Preserve Metadata", and "Preserve color profile") both are ticked. Is there an easy explanation for this behavior?
Sorry but i don't understand, what's the problem with file size?
(2)
The latter brings up another question (not sure if it makes sense, but I try): which specific "color profile" is meant in that latter option?
"Preserve color profile" is used to keep the color profile in the image file (if any)
Pierre.

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Re: Counter-Intuitive Behavior of File Size

Post by XnNewbie » Mon Mar 12, 2018 1:37 pm

when you add pixels to an existing file, by increasing the pixel size of that original file, the resulting file size must increase, not decrease; unless you changed something in the content of the original file, which should not be the case at all by just adding pixels

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Re: Counter-Intuitive Behavior of File Size

Post by xnview » Mon Mar 12, 2018 2:17 pm

all depend of compression, and perhaps you have metadata not supported
Pierre.

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Re: Counter-Intuitive Behavior of File Size

Post by cday » Mon Mar 12, 2018 3:43 pm

XnNewbie wrote:when you add pixels to an existing file, by increasing the pixel size of that original file, the resulting file size must increase, not decrease; unless you changed something in the content of the original file, which should not be the case at all by just adding pixels
xnview wrote:all depend of compression, and perhaps you have metadata not supported
The TIFF format supports a number of different compression methods, all of which other than JPEG are lossless, so if you are resaving using one of the lossless options the original image is identical to the original whatever the file size.

The format and compression method used when saving is set on the Output tab, so you can check which method is beings used. Otherwise, as Pierre says, some other factor such as metadata that can't be preserved must explain the slight decrease in file size.

Note: For completeness, in some circumstances when the compression method used is changed, the resulting file size can be much smaller, still with an identical image.

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