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Old Feb 7, 2003, 8:56 AM   #1
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Default Jpg quality question......

Hi,
I have been confused about this one for awhile now.... I'm wondering about jpg's and quality after I edit them. Here's what I have been doing..
I download the photo from my camera, it downloads as a Jpg.
Then I will usually do a little editing, such as cropping or enhancement. I resave the picture as a jpg. I save the photo to a cd, and take to the store to get prints made. Did my photo lose quality because I saved it as a jpg after editing??

Not sure I understand how I should be doing this. It downloads from my camera as a jpg, then after I edit, should I save it as a tiff, or bmp?

Thanks,

Terri
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Old Feb 7, 2003, 9:15 AM   #2
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Terrilp,
you can save as TIFF if your lab takes this format (mine doesn't). Or you can save as JPEG: at high quality setting you won't have any trouble unless your prints are huge (20"+). If yor final JPEG file is approximately the size of original from camera then you probably used the same level of compression. You can try from this point to increase compression and see if there's any difference on prints. Doesn't make much sense to use less compression than in camera, picture won't get any better.
Sergey
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Old Feb 7, 2003, 9:44 AM   #3
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Every time you re-save a Jpg it loses quality depending on the compression setting - make sure it's set to the min compression - two or three re-saves at min compression will be ok.

I suggest you save the images on another CDR before you do any editing then you'll always have the originals to fall back on.
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Old Feb 7, 2003, 9:57 AM   #4
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Every time you save as jpg you recompress the image.
Since jpg is a loss-y compression, multiple things will happen including loosing data, more/larger jpg artifacts and (probably) other problems as well.

A good work flow is (from what I've seen people post here):
Copy the jpgs from your camera/media to your computer.
Make sure they are not corrupted (the thumbnail isn't enough for this.)
Back it up (CD's seem the most common/logical choice)
Write protect the original on your hard disk
Copy the jpg to a work area
Load it in your favorite editor and immediate save it to a loss-less format (photoshop's proprietary format, BMP, TIFF....)
Edit to your hearts content.
Save to a format chosen for your use (jpg for the web or email, for example.)

This way you can save it multiple times while working and not recompress it and loose data. Also, some people suggest formatting your media in you card after you have downloaded (and verified) everything instead of "deleting" the individual pictures.

This is more than what you were looking for, but hopefully it helps.

Eric
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Old Feb 7, 2003, 12:39 PM   #5
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Just a clarification:

Copying a file from hard drive to a CD is not considered doing "a save". You only loose quality if you actually open the JPEG in some sort of program, then save/re-save it from within that program
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Old Feb 7, 2003, 4:04 PM   #6
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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 7, 2003, 8:49 PM   #7
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Thank you so much for all your answers.. I knew I would find help here!!! Now i'm off to read the faq on jpg's...

Terri
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Old Feb 8, 2003, 11:58 AM   #8
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Not sure about other camera programs but with the Fuji FinePix Viewer that came with my S602 you can upload your photos from the camera in the TIF or BMP format and both are non-loose type files. Make any changes or corrections and save as a JPG on you drive of choice. You should check to see if you camera program offers this feature.
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Old Feb 9, 2003, 6:33 PM   #9
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I take my cd with the edited photos to Costco to get prints because they have the outstanding Fuji Frontier processor printing on archival quality paper, for all of 19 cents for 4x6, and 2.99 for 8x12. Can't beat that, that I know of. They take tiffs, so I save all mine as tiffs on the cd, with no loss of quality. If you have a Costco close enough, tiffs make more sense, although you don't lose much quality with one jpeg save.
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Old Feb 10, 2003, 5:27 PM   #10
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Quote:
Not sure about other camera programs but with the Fuji FinePix Viewer that came with my S602 you can upload your photos from the camera in the TIF or BMP format
Just a bit of clarification here, What the program does to the file is slightly irrelevant. The 602 like most cams, captures and converts to JPEG files in the cam. (unless you select the highest quality TIFF format, which is too slow and memory hungry for most). Unfortunately the JPEG 'damage' is already done in the cam!

The first import into any editing package is actually a bitmap - which is why it is so big in memory (2 copies). It's what you do afterwards on the save that's important. This is when you can choose to 'save as' JPEG or TIFF/BMP- if you have the storage space. Most of us who keep an original would probably save copies as a high quality JPEG. But I admit, if I'd spent hours retouching a pic. I'd consider a BMP- in case of further editing or re-sizing. FinePix Viewer is not doing anything special or spectacular!

PS Frontier 6X41/2 (yes 41/2 no crop!) in UK are Brill.
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