Author Topic: Thumbnails of large images turn into color bands  (Read 7842 times)

Offline stangolde

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Thumbnails of large images turn into color bands
« on: April 25, 2006, 04:30:00 am »
When I bring up a folder of images which include some that are 20 x 30 inches the thumbnails for the larger images turn into color bands while the smaller thumbnails of 13 x 19 images are just fine. How do I protect the larger thumbnails from from becoming banded patterns? Can I reclaim the thumbnails that are just vertical bands of color?

Thanks,

Stan

Offline Kirk Baker

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Re: Thumbnails of large images turn into color bands
« Reply #1 on: April 25, 2006, 07:08:35 am »
When I bring up a folder of images which include some that are 20 x 30 inches the thumbnails for the larger images turn into color bands while the smaller thumbnails of 13 x 19 images are just fine. How do I protect the larger thumbnails from from becoming banded patterns? Can I reclaim the thumbnails that are just vertical bands of color?

What are the actual pixel dimensions of the files?  What file format are the files?

-Kirk

Offline stangolde

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Re: Thumbnails of large images turn into color bands
« Reply #2 on: April 25, 2006, 07:04:38 pm »
The actual pixel dimensions are 4800 x 6574 pixels in Photoshop psd format with multiple layers. The file size is around 800 megs.

Offline Kirk Baker

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Re: Thumbnails of large images turn into color bands
« Reply #3 on: April 25, 2006, 07:23:20 pm »
The actual pixel dimensions are 4800 x 6574 pixels in Photoshop psd format with multiple layers. The file size is around 800 megs.

We use QuickTime to load PSD images.  It does have its limitations and while I don't think your pixel dimensions are too big, it may just be that the overall file size is too large for QuickTime to handle.

We plan to write our own PSD parser in the future which will still require PSD images to be saved with a composite layer (Maximize Compatibility must be on when saved) but will be faster and will handle larger images.

-Kirk

Offline stangolde

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Re: Thumbnails of large images turn into color bands
« Reply #4 on: April 26, 2006, 02:41:04 pm »
What's so strange is that the picture with the large number of pixels shows up fine at first then in a few minutes with changes right in front of your eyes to the color bands.

Stan

Offline Kirk Baker

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Re: Thumbnails of large images turn into color bands
« Reply #5 on: April 26, 2006, 03:26:57 pm »
What's so strange is that the picture with the large number of pixels shows up fine at first then in a few minutes with changes right in front of your eyes to the color bands.

That's because we ask for a thumbnail first to get something on-screen as fast as possible and on the second pass we ask for a high quality representation.  That's when QuickTime is choking.

You can make it so that PM doesn't generate high-quality thumbnails, by unchecking the "Generate high quality thumbnails" checkbox in the Contact Sheet tab of the Preferences dialog.

It will be much faster and won't bother to load the high-quality thumbnails that don't work for you anyway.

HTH,

-Kirk