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Old Feb 8, 2003, 1:02 AM   #1
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Default Win XP picture and fax viewer have lossless jpeg rotation?

Hi Folks,

Windows XP opens images in the My Pictures folder and then you can use the Windows Picture and Fax Viewer to quickly run through a large view of the images to delete the bad ones. You can also rotate them, but does anyone know if this is a lossless rotation? I've been reluctant to use it, presuming that it would probably not be lossless. It would be so convenient to be able to use it right there, though, so I thought I'd ask. I don't edit every one of my photos in PSE, so this feature would be nice in that instance. I wonder if anyone might know. Thanks.
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Old Feb 8, 2003, 2:37 AM   #2
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Woohoo, I'm actually able to answers someone's question. Unfortunatly the answer is no. Per Micro$oft's own XP digital imaging page at http://www.microsoft.com/WindowsXP/d...ettingupxp.asp


Rotate in an image editor. The Filmstrip view in My Pictures, and Windows Picture and Fax Viewer, feature the ability to rotate photos left or right. This is a handy way to turn upright a flopped vertical. But, in many cases, itís better to perform this rotation at another point in the digital workflow, especially if youíre trying to preserve every ounce of image quality in the original photo. This isnít true for all formats, but it is for JPEG and many RAW formats. Hereís why:

If a JPEG is rotated in My Pictures or the Windows Picture and Fax Viewer, itís resaved. Every time a JPEG is resaved, the image is degraded slightly. The best time to rotate the picture is when itís being adjusted in an image editor, since it has to be resaved anyway (and it can be resaved in a format like TIFF, where no additional quality loss is incurred).

If a RAW file is rotated in Windows Picture and Fax Viewer (in most cases, the rotation buttons in My Pictures are disabled when a RAW file is selected), chances are the high-resolution RAW picture data will be lost in the process. In general, this will happen with RAW files that use the TIFF file structure. This includes RAW files from the Canon EOS-1D, Nikon D-series, and Kodak DCS series cameras.
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Old Feb 8, 2003, 7:46 AM   #3
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Look here:

http://jpegclub.org/
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Old Feb 8, 2003, 7:22 PM   #4
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Please note also that when you rotate images in XP, like many other pic editing software, it strips out the EXIF data! So, if you want to keep this information in the saved JPEG file, make sure you are using a software package that preserves EXIF data.

Follow-up 2/10/03 2:08p:
Oops! I stand corrected! Thanks, TimT for pointing out my mistake-- I must have used CompuPic to save the file. Rotating does NOT strip the EXIF data when done in XP. :?
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Old Feb 9, 2003, 12:49 AM   #5
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Gee fellas, I don't know. I posted this over on the XP Photo newsgroup as well, and take a look at the confusing answers there:

http://communities.microsoft.com/New...ndowsxp.photos

I don't have a printer, but I tried Yves Alaries suggestion somewhat: 20 rotations of a jpeg in the XP Picture and Fax Viewer, some clockwise and some counter, and then viewed it at at 100% in Elements. I could detect no degradation.

It's hard to argue with Tim's link to the XP description of it's own features, isn't it? But I'm not seeing it on my monitor. Also, lg, the exif data is still there after all these rotations, when viewing it in Elements.

Here's more: I also posted this (I can hear it now...way too much time on his hands) on the Adobe Elements forum and got this link to even MORE confusing discussion:

http://www.adobeforums.com/cgi-bin/[email protected]


I think Yves Alaries is right. Compare prints of a jpeg negative and a copy, after it has been rotated many times in the Picture and FaxViewer. Anyone with a printer out there curious enough to try it?
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Old Feb 9, 2003, 2:46 AM   #6
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There's no doubt that the rotation is not lossless and that XP is actually writing to the file You can rotate your image over and over again and see the difference in filesize. XP does however preserve the EXIF, and doesn't change the file's modified timestamp. A tricky bit of subterfuge indeed. As for not being able to see the loss that is probably going to depend on the size of the orginal image and the eye examing the image. A large image even saved many times will not exibit much visible loss when printed or even viewed full size(as oppossed to zooming in on a certain area). I would wager most people would not be able to discern the difference. However the loss is still there and to some people every pixel counts, to others it might be convienent enough to outweigh the undiscernable loss. Anyway, I'm rambling by now. For you enjoyment a couple images. A 309 x 312 (resized to 440x445 to better see the lossiness) crop of my baby daughter's eye. The first has actually been saved a few times in the gimp(one to remove redeye the other for the crop, lastly to resize), and the second is that image rotated 32 times with XP's image rotation(not that anyone would actually do that, simply a proof of concept). I'm definatly going to have to stick with lossy...

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Old Feb 9, 2003, 6:40 AM   #7
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A few jpeg peculiarities independent of XP:

Quote:
FYI, see subject #10: http://www.faqs.org/faqs/jpeg-faq/part1/

Quote:
Subject: [10] Does loss accumulate with repeated compression/decompression?
...There are a few specialized operations that can be done on a JPEG file without decompressing it, and thus without incurring the generational loss that you'd normally get from loading and re-saving the image in a regular image editor. In particular it is possible to do 90-degree rotations and flips losslessly, if the image dimensions are a multiple of the file's block size (typically 16x16, 16x8, or 8x8 pixels for color JPEGs)...

...It turns out that if you decompress and recompress an image at the same quality setting first used, relatively little further degradation occurs. This means that you can make local modifications to a JPEG image without material degradation of other areas of the image. (The areas you change will still degrade, however.)...
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Old Feb 9, 2003, 8:41 AM   #8
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C'mon, Tim...I know this is a techncal thread and not an artistic one, but...

Show us the full pic of your cute little daughter!
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Old Feb 9, 2003, 12:01 PM   #9
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I'll just post a couple links as to not clutter the thread up too much...

Cute baby #1(Anna)
http://users.tcworks.net/~ttempl/HPIM0254.JPG

Cute baby #2(Emily)
http://users.tcworks.net/~ttempl/HPIM0484msk.jpg
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Old Feb 9, 2003, 12:06 PM   #10
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Tim, you,ve put it to rest. Thanks for the insight.

NHL, that was a very informative site. Thanks. I read the whole thing, and learned a lot.

Stu, among all us scholars here, you must be the Ray Romano one.
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