The problem with JPEGs:
Big issue...every time you edit a jpeg and save it, there's loss. The only way to prevent images you update often from crapping out with time is to save another copy in a lossless format. JPEGs are created by storing the spectra (frequency content) of images rather than the graphical data itself. The images are 'compressed' by deleting high frequency values. The more frequency information you remove, the smaller the file. If you kept all the frequency information, the file would be as large as (possibly larger than) a bitmap of the same image. JPEGs are only good for transferring images. I much prefer to keep my pictures as bitmaps until I've edited everything I need (scratch removal, red-eye, etc.), then I convert to a JPEG.
You can't even resize or crop a JPEG without loss (mathematically impossible). The only thing you can do to a JPEG without loss is rotate it 90 or 180 degrees in either direction. The lossless method is not performed by most image editors. Windows Picture and Fax viewer will do it though. (Attached is the image of the button you should press.)
What image format do you like best?
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- Master Jedi
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To follow-up what Master Jedi was saying. I saw a tutorial on TechTV about digital imaging and they said the same thing Master Jedi was saying. Basically, everytime you open up a compressed digital image and manipulate it and save it again, you are removing more data from the image composition and the image is using algorithms to "fill in the gaps". It's like making a photocopy of a photocopied document. Eventually, the quality gets so crappy, it's horrible to look at.
The suggestion from TechTV is to always have a version of your image in a lossless format. Then you make your changes to the master, save it again in a lossless file-format (so you have a new jumping off point for future changes), and then save it in the file-format of your choice.
To answer insomica's question. I believe TIFF files are much larger than the other compressed file formats. It may be a large enough difference to say TIFF (I'm not sure if it is a lossless format) compared to JPG's are like WAV files compared to MP3's. Many reviews of digital cameras suggest you get cameras that take images in TIFF format, but they are hard to find, and you can't get very many pics on a storage card compared to JPG or BMP.
The suggestion from TechTV is to always have a version of your image in a lossless format. Then you make your changes to the master, save it again in a lossless file-format (so you have a new jumping off point for future changes), and then save it in the file-format of your choice.
To answer insomica's question. I believe TIFF files are much larger than the other compressed file formats. It may be a large enough difference to say TIFF (I'm not sure if it is a lossless format) compared to JPG's are like WAV files compared to MP3's. Many reviews of digital cameras suggest you get cameras that take images in TIFF format, but they are hard to find, and you can't get very many pics on a storage card compared to JPG or BMP.
- Timelessblur
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I hate to bring a dead thread to life but I read something recently that could really add to this topic.
In popular science a month or 2 ago they stated do not use BMP to save file types in since that file type is not expect to be around much longer and my become unreadble by future veiwers. It went on an explain the problems with the jpeg and nto to save types like that do to the quilty lose. It stated use the TIFF file type if you want to keep the quillty. Also there is one other file type that some digital camras can use that is also quite good for photos but I can not remeber it name. The draw back to it was not a large number of viewers can read the type yet due to its newness
In popular science a month or 2 ago they stated do not use BMP to save file types in since that file type is not expect to be around much longer and my become unreadble by future veiwers. It went on an explain the problems with the jpeg and nto to save types like that do to the quilty lose. It stated use the TIFF file type if you want to keep the quillty. Also there is one other file type that some digital camras can use that is also quite good for photos but I can not remeber it name. The draw back to it was not a large number of viewers can read the type yet due to its newness
http://www.myimgs.com/data/timelessblur ... omulan.jpg
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