Crop changed due to different 'original size' of images

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Crop changed due to different 'original size' of images

Postby Laika » Mon Dec 01, 2014 12:17 pm

Dear OO users.

When opening impress .odp files on different installations on different machines, cropped images appear totally screwed up.
The problem originates from the interpreted size of the imported images:

On computer A, a certain image with pixel dimensions 3500x2000 has size 92,60cm x 52,92cm
On computer B, the same image with pixel dimensions 3500x2000 has size 74.08cm x 42.33cm
(read from Format | Crop when selecting the inserted image)
(this is the case with .png and .jpg images; probably other formats too, but untested)

Now, crop settings are defined as distances in cm from the image borders. So, if the images have not the same 'original size', the selection defined by the crop is not the same either... and that screw up the image sin the presentation when the files are read on another computer.

How does Impress decide on the dpi resolution of the imported images? How can we, as users, influence that interpretation? Is there a setting associated with it?

thanks in advance for any help,
best regards,

Laika,
still orbiting
OpenOffice 3.4.1 ; Windows 7
Laika
 
Posts: 3
Joined: Tue Jul 08, 2014 10:09 am

Re: Crop changed due to different 'original size' of images

Postby Laika » Mon Dec 01, 2014 2:46 pm

Dear OO users,

upon further investigation of this problem, it appears that Impress interprets inserted images as being of the dpi-setting as currently used by the MS-Windows desktop settings!
If your desktop's resolution is set to be 96dpi, the size of an inserted image of 3500x2000 pixels is 3500/96 inch x 2000/96 inch, or 92,60cm x 52,92cm.
If you open that same odp-file on a machine with desktop settings to be 120dpi, the image's original size is interpreted to be 74.08cm x 42.33cm.
With the same crop settings, expressed in cm, the result looks completely screwed up.

This is not dependent on the version of OO; also LibreOffice and an old StarOffice exhibits the same problem.

When desktop viewing settings are changed, the odp file looks completely different.

Why is it that a desktop resolution setting affects the actual behavior of OO Impress?
Why is it that Impress wants to attach a size to an image that in it's core is only defined as a number of pixels. The dimensions in cm in the odp file is completely arbitrary, as there is even no connection with how it is printed or viewed on the screen.

On would think that an image with a pixel size is treated as an object with pixel-size. A crop definition then would be using either a pixel-dimension or relative measurements. And if for some reason a dimension in absolute units like cm is to be attributed, one would think there is a setting to control how this is done.
But I cannot find such setting or parameter.

One would also think there are plenty of forum posts around the internet about this problem, as one would think this affects many people. I cannot be the first one to run against this issue.

thanks in for any comments and help,
kind regards,

Laika,
still orbiting
OpenOffice 3.4.1 ; Windows 7
Laika
 
Posts: 3
Joined: Tue Jul 08, 2014 10:09 am


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