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Can you explain file size....


L

Lynny

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Why is it that the file size changes so much,

why when you open a digital photo in PS, and do nothing, and save it does it get bigger..... ??
Why when you flip it 90degress does it get bigger still??
And when you "save as" at say 7 close it...then open it and "save as" at 10 does it get bigger..... where do the extra kb's come from......why didn't they count when it was saved at 7..... there are lots of examples of a file changing size, when really you have done nothing to it...... and I have often asked, but never recieved a reply that makes sence.....

Any ideas....

Lynn
 
I am only guessing here but I would say..............

it's all down to history..................

when you open a file and look at your history layers (breath mark) there you will find a layer that says open file.......... could this be it?

if you are to turn the image 90 degrees ............ look again at your history layers (breath again mark he he he) there you will find your action which you can undo

so my guess is that it stores it in memory or history so that it can be undone.
sfm
 
Lynny if i get you right you're
saving in PSD
saving inother format "compressing/not compressing"
adding new layer
adding new channel
history states as smf said..

thing s like this cause increasing of the file size. my advise to you is to view document size from the status bar (win) image bar(mac) so this way you'll keep an eye on your document size, how it was and where it's heading.

i hope this helps.


Ammar
 
Ammar this is what has me stumped..... I'm not doing anything except saving as a jpg.. typical scenerio....I'm doing it now so I can tell you the kb's exactly...

Open a jpg. 747kbs
Save as... at setting 12.. closed the image...go to saved image, it is now 1350kbs... why?
Image, rotate image 90 degrees, saved as setting 12....closed file.... go to saved image it's now 1360kbs....again why does this happen?
Another photo, started 698kbs, flip it 90 degrees saved it, closed it, check size it's now 868kbs.....

I sit confused..... if I had done something besides save it under a new name I would understand it........

If you open the same image and save it again, the size doesn't change the second time.

It's just the first time you save after loading digital photographs into the computer that they get so much bigger when all you are doing is changing their name and resaving them.

sfm, I was talking about once it was saved, closed and then opened again, then it's bigger..... there's no history on a jpg once it;s closed... or is there???....

Lynny
 
Well Lynny, I did a test with a 100 kb Jpeg, opened it and saved it as test1.jpg, with a quality of 60. Then I closed all open files.

Then I opened test1.pg, flipped it and saved it as test2.jpg, with a quality of 60.
Then I opened test1.jpg, rotated it 90 degrees and saved it as test3.jpg, with a quality of 60.

Final result: all files have the same size.

I also did a test with a PSD file: after I rotated it 90 degrees, the files size was bigger, after rotating it back 90 degrees, I had the same size like in the beginning.

I don't understand what you mean by Saved As... with setting 12 [confused]
I don't have that option in PS7, but I do have an option to change the quality of JPEG between 0-100 when I go to Save for Web.... A quality of 12 would be a rather bad quality (!), so you must have meant something else.

Also, don't forget, that it all depends on the quality this JPEG file was originally saved with. If it was saved with 60 and you save it with 80, then the size will grow, if you save it with 50, it will be smaller.

Important question is where you checked your file sizes. In my test I checked the size in explorer, not in Photoshop.
 
Gauss, I guess she is saving using save as, not save for web. there you can choose from 1 -12.

Sometimes, flipping (or not) an image will reduce its size bur to the patters that would compress better. Try to make a square image with horizontal lines in gif , save it, then save a copy flipped 90 degrees with the same settings...

The image might be saved using advanced compression settings (baseline, etc...)

Adding a profile increases sometimes the image size dramatically (on the first window of the save as)

Also, If you save in PSD, you have the choice to add a flattened copy or not .

This increases the size, but will allow you to open the flattened version of the image (hold down SHift+CTRL+ALT while opening the pic) to fix the blending modes, in case the change it in some way in future versions... it will also allow faster preview in file viewers, or to open the flattenede version faster (just to show to a client, for instance)

We've seen also that hiding every layer reduces the size when you save in psd... strange, but worth trying...

I was also lucky Zipping tiffs images (instead compressing during the save process, the latter could produce unreadable zips in other programs)
 
You probably have the option on to save a thumbnail so you can preview the jpg in the open dialog box. This increases the file size.
 
No, the problem is when I first save after I download from a digital camera, thats when the big changes happen. They download as a jpg, I rename them and save again, as a jpg and the grow.... I could upload a picture that straight from my camera and you could try it, but the are about 750kbs each so maybe not.

Lynny
 
Like I said earlier, it all depends with which JPEG quality setting the file was originally saved. If you save it in PS with a larger quality setting, then the file size will shrink, save it with a higher quality setting and the file size will grow, it's the way JPEG works; http://www.help-net.com/computer buddies/what_is_a_jpg.htm

But you shouldn't save files in JPEG, because it uses a "lossy" compression. TIFF is a better choice.
 
Gauss said it best:

But you shouldn't save files in JPEG, because it uses a "lossy" compression. TIFF is a better choice

Nor should you work with a jpg file at all. The format is meant as a final save for the web, not as a file you should flip, rotate, filter, color correct, twirl, squeeze or otherwise torture its pixels :) The JPG format is lossy, which means exactly what it says. And every time you do something to a JPG file, it does the best it can...really.....but there's only so much it can do.

My GUESS of what's happening here, is that the format is trying to accommodate you, but simply cannot. You're asking something of it that it wasn't meant for, and when you do that to any image file, it can do strange things :)

Like Gaussian said, grab the original file, if you have it. Save as a tiff (or .psd) Play around with it then. Never play around with a jpg file.
 
Just thought I'd mention, in addition to .tiff & .psd formats, you can also use .png, and those work on the web like .jpg & .gif as long as they're being viewed with a newer browser. The downside is that they do have larger file sizes since it's a loss-less format. The upside is that you don't loose any data when you save, and you don't get those ugly blotchies as with a .jpg.

I'm probably being redundant here. Back to work!
 
SUE!...

(breath mark)
Click to expand...

hahaha you are SO asking for it girl! [slick] [sly]

Another thing to bear in mind about this guys is that everytime you save a JPG from PS, it adds it's own garbage into the header code of the image. This too will increase file size. By how much? Don't know exactly...

And no, there's no way to prevent this in case you're wondering.
But there ARE small JPG 'code stripping' apps out there that can remove the headers from a JPG. Don't know anymore where one might find these though.
 
Hi e__ and welcome to the board :righton:

I downloaded the program and might give it a try later on and post the results.
 
I tried the program and gained a silly 35 bytes on a file, saved as JPEG in Photoshop. Not very shocking I might say :\
 
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