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Pixel aspect ratio problem in gif files
Posted: Thu Oct 19, 2006 12:48 pm
by sam
I recently resized and converted a large batch of tif files to gif format. In doing this, I seem to have mangled the "pixel aspect ratio." The majority of image display programs (including XnView) have no problem with this, and display the images as I expected. But, unfortunately, when printing the images from Internet Explorer (which displays the images correctly), the images are truncated.
Also, when attempting to print from the "Windows picture and FAX viewer", the aspect ratio problem is super-exaggerated.
Is there a way to correct the aspect ratio (to square pixels) in XnView or nconvert?
Re: Pixel aspect ratio problem in gif files
Posted: Thu Oct 19, 2006 6:32 pm
by xnview
sam wrote:I recently resized and converted a large batch of tif files to gif format. In doing this, I seem to have mangled the "pixel aspect ratio." The majority of image display programs (including XnView) have no problem with this, and display the images as I expected. But, unfortunately, when printing the images from Internet Explorer (which displays the images correctly), the images are truncated.
Also, when attempting to print from the "Windows picture and FAX viewer", the aspect ratio problem is super-exaggerated.
Is there a way to correct the aspect ratio (to square pixels) in XnView or nconvert?
You can use resize
Posted: Fri Oct 20, 2006 12:38 pm
by sam
Pierre, is there an "pixel aspect ratio" option in resize? I couldn't find one.
The original steps I took were:
1) Start with large b/w tif (e.g., 2600x3900, scanned at 300dpi)
2) Resize with XnView (set height to 1200, 'Keep Ratio' checked, Lanczos resample method selected.)
3) Save result as gif, 8-colors.
4) Result looks fine in XnView and most other image viewers.
5) Open file with 'Windows image and fax viewer', select print icon, resulting print output has aspect ratio problem (image is extremely narrow).
6) Open file with photoshop 8.0, image is also extremely narrow. Select "Image -> Pixel aspect ratio-> Square" in photoshop and image looks correct. Save file as gif from photoshop and print from Windows image and fax viewer, output looks correct.
So, I can 'fix' the images with photoshop, but I'd prefer to avoid this step in my process. (Unfortunately, some of my customers use Windows picture and fax viewer to print images, so avoiding that application is not an option for me.)
Posted: Fri Oct 20, 2006 3:02 pm
by Olivier_G
Could it be due to a X/Y resolution difference? (ie X <> Y)
What values do you have in Menu>Image>Set DPI with that opened file?
Posted: Fri Oct 20, 2006 4:53 pm
by sam
Both x and y values are shown as "72". If I then open the image in photoshop 8 and do: "Image -> Pixel aspect ratio-> Square", save the file, and reopen in xnview, the DPI values are still shown as "72".
Posted: Wed Oct 25, 2006 8:22 am
by xnview
sam wrote:Both x and y values are shown as "72". If I then open the image in photoshop 8 and do: "Image -> Pixel aspect ratio-> Square", save the file, and reopen in xnview, the DPI values are still shown as "72".
Is it possible to have the file?