After editing JPG, the file is much smaller! HELP!

[newbeephotographer]

HI!

I have googled this problem and I have browsed through all these forums for an answer that I couldn't find. Maybe you guys can help me?

I shoot with a Canon EOS XS

I shoot in JPEG. My original files are around 6mb each.

After I edit the jpg pictures they come out to be about 1mb or less!

I use corel paintshop pro4 and I checked the setting and made sure nothing compresses the files after being saved.

Is is true that as you edit jpg files it just compresses and you lose image quality?

Another thing I have tried was to convert the jpg into a png and then edit the png file and then save it as a png file which results in files that can be up to more then 10mb.

I must be doing something wrong. Is anybody else having this problem? if not, how do you edit and keep the image size the same?

[ceremus]

Generally the size of the file will be affected most by the amount of compression applied to saving the file, and usually when saving under JPEG you should see an option to level the amount of compression, or sometimes referred to as the "quality" of the saved file. JPEG is a lossy format, so every time something is saved as a JPEG there is some data loss. Greater levels of compression will result in the file throwing away more data from the original.

Otherwise, the overall output dimensions (the size of the image) will have the other most dramatic impact on the file size.

Formats such as PNG and TIFF use lossless compression, they retain all of the original image's color data, resulting in a larger file.

[kcoppock]

Originally Posted by newbeephotographer

HI!

I have googled this problem and I have browsed through all these forums for an answer that I couldn't find. Maybe you guys can help me?

I shoot with a Canon EOS XS

I shoot in JPEG. My original files are around 6mb each.

After I edit the jpg pictures they come out to be about 1mb or less!

I use corel paintshop pro4 and I checked the setting and made sure nothing compresses the files after being saved.

Is is true that as you edit jpg files it just compresses and you lose image quality?

Another thing I have tried was to convert the jpg into a png and then edit the png file and then save it as a png file which results in files that can be up to more then 10mb.

I must be doing something wrong. Is anybody else having this problem? if not, how do you edit and keep the image size the same?

You don't. If you're changing the image, the file size will always be at least slightly different.

As for JPG, it uses a lossy compression algorithm, so yes, your file will be smaller, and lower quality each time you save it, regardless of the quality setting you choose. Obviously the effects will be less severe at a higher quality setting, but there's still a loss of quality.

PNGs are compressed, but with a lossless compression algorithm (nothing changes visually) so for the same image, you'll usually end up with a higher file size than the JPG.

Editing and saving TIFFs will maintain the highest consistency (lossless, usually uncompressed, but optionally compressed), but at the expense of a very high file size.

Always work from the original if possible!

[Doug Sundseth]

First, it's not compression that's the problem. There are lossless compression algorithms (LZW is commonly used on TIFFs for instance) that do not degrade image quality at all, regardless of how many times you compress and expand. But .jpg files use a lossy algorithm. It's inherent in the file type. The only question is how aggressive (and lossy) the compression is. With PS, I get to choose the compression quality when I export; I'm sure there's some place you can choose that in Paintshop Pro as well.

Second, if you're cropping, your final file can be much smaller than you think it might be. If you start with a 4x6 and crop 1" off of top and bottom, the final file will have about 40% as many pixels as the original.

Third, if you do a lot of smoothing (for instance; there are other things that can do the same), it's possible to create a file that works better with the compression algorithm so you can get a smaller file without a great deal of loss in IQ.