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Old Jan 31, 2013, 9:27 AM   #1
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Default JPG files and subsampling

OK - here's an interesting issue. My girlfriend wants us to be able to display our photos on the TV. We have a panasonic plasma and blu-ray player that both have this capability. Regardless of how the image gets to either device (either sharing from the computer or jump drive or memory card) I have the same problem:
All the images show up as thumbnails but when the slideshow starts any image that I have updated (I use photoshop) will not display - the device says "Unable to display". If it's a jpeg strait form the camera it displays fine. Talking with panasonic they provided the following criteria for an image to display:
Sub-sampling - 4:4:4, 4:2:2 and 4:2:0
Image resolution - 8 8 to 30,712 17,272 pixels

The resolution isn't a problem - I've tried very small. Which leaves the sub-sampling. The problem is I don't know how to tell what the values used are. Not using photoshop is simply out of the question. But clearly something is happening in the save process which results in a subsampling that is not one of the 3 "acceptable" approaches.

Anyone have any thoughts or ideas on how to proceed?
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Old Jan 31, 2013, 11:00 AM   #2
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When you save a JPEG, you can set various options for the file. 4:4:4 and the like are options from that menu. I don't use PhotoShop, so my comments will be of a general nature about JPEG compression.

First, use Baseline JPEG if it is available by name. This is the most generic form of lossy JPEG compression, and should be compatible with most applications.

Second, there is such a thing as "lossless" JPEG. A fairly large number of applications have trouble with that. So make sure you have not selected that.

Third, it is possible to select more than 8 bits per channel for JPEG compression on some applications. Most display applications will have trouble with any bit depth greater than 8.

Fourth, make sure you're not using Adobe color space. This should only make the colors look bad on a TV, but it is possible that some of the colors would be out-of-range and make the display application misbehave.

It would make sense to avoid things like progressive and heirarchical encoding options. These are more sophisticated encoding methods that may create problems for the most minimal applications. If the options menu referred to above does not use the word "baseline," it may use the term "sequential." That would be the one to choose for maximum compatibility.
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Old Jan 31, 2013, 11:21 AM   #3
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Thanks - I couldn't find anywhere to set the 4:4:4 or whatever. But, I am using a progressive - so when I get home I'll see if there is a "baseline" or "sequential" option. That would be good. I could then run a batch and create copies for TV display using that option if it works.
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Old Jan 31, 2013, 12:06 PM   #4
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I use Photoimpact, and it gives me options of 'Standard', 'Progressive', and 'Progressive optimized', as the jpeg saving options, with slider for compression amount. I recall having problems displaying the progressive jpegs on a digital frame, so that could very well be the problem.

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Old Jan 31, 2013, 4:39 PM   #5
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Well the good news is changing the jpeg save to "standard" works. Unfortunately I can't quite get a batch script working that does this. So, I'm past the first problem - now I just need to solve the "batch" side so I can convert a bunch of images for viewing.
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Old Jan 31, 2013, 9:22 PM   #6
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Have you tried using Irfanview for this? It supports just about anything you would want to to with a batch file.

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Old Feb 5, 2013, 10:45 AM   #7
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Irfanview did exactly what I wanted! Thanks for that!
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