Help! Is paint.net compressing my image sizes against my will?

[rosequartz]

Hi - I really hope someone can help. I need hig res images for printing (at least 300 dpi) but two things have happened that make me think paint.net may be compressing images without my knowledge or consent...

the first is that an assistant redid an image for me (that actually i had first created in paint.net at too low a resolution) using photoshop. The image was 1398 by 1044 pixels. He saved it as a tiff and it was 4MB. I then opened it in paint.net, checked in "resize image" to make sure it was those number of pixels - did not change a thing - and resaved it under a new name again as tiff from paint.net. Now the image is ONLY 222kb!!

QUESTION: Did it compress the image?? It still says it is 1398 by 1044. 4Mb from photoshop did seem awfully large, but 222kb seems very small for this line drawing. Can you please tell me what is going on? if paint.net has compressed all my images so that they are no longer hi res I am really screwed...

Is this image still 300 dpi? Will it still look good when professionally published? Why did it make it so small?

Then a second thing happened. I set the default program for all jpgs and tiffs on my computer to open from paint.net (!). Was this a huge mistake? now when I look up each file, it lists all jpegs and tiffs as "paint.net" images even if they were not created this way. I tried chaning the default program back to something else, but it still says all of my images are "paint.net" even though most of course were not created with paint.net. So the biggest worry is that when i changed the default, not only did it change their descriptions to paint.net files but it also COMPRESSED THEM!

Since I didn't look at the file sizes before, I cannot tell if they are now smaller. I do note that a cartoon that i paid to download at 757 by 900 pixels (a jpg) is now only 48KB. I do not know if it was bigger before. so, QUESTIONS:

by chaning the default opening program on all my tiffs and jpegs to paint.net, has it compressed my images so that they are not longer as big or as hi res as before? (does 48kb for a jpeg of that size seem like its been compressed by paint.net?)

sorry for the long post or if the tone is off - I really am desperate here. help - especialy reassurance - would be much apppreicatied. I sure hope I am wrong. If it did compress is there anything i can do or is years of jpgs and tiffs now hoplessly useless? (you can see the desperation if so...)

[pdnnoob]

I will tell you right now that, if your images were 4mb each, your hard drive was really getting ripped off. A 4mb image on my computer tends to be approximately 4000x4000 pixels. Don't worry, you didn't lose any details or image quality if you saved as a .tiff or .png

[Rick Brewster]

I'm not sure you're worried about the correct thing.

"Compression" is simply a way of making something smaller. There are many ways to do this, some which retain 100% fidelity (PNG uses such a technique), and others which sacrifice fidelity for smaller file size (like JPEG). The latter is what you should be on the watch for, as the former will never cause any trouble or grief to anyone. Not even a puppy.

However the "physical" size of the image will not change through any of this. The # of pixels will be the same.

If you want to verify that the content of two images are the same, load them up into 2 separate layers in a new image (as in, FIle -> New Image) and set the top layer to Xor blend mode. If it's pure black, then they're identical.

[Sozo]

That's a neat trick Rick. Also, when your computer calls them Paint.NET images, it is just referring to the program it uses to open that particular filetype. It does not mean that Windows has snuck around your harddrive resizing images while you weren't looking.

No information in the images is changed just by setting the filetype association to Paint.NET.