Why are the file sizes inconsistent when saving files for web / other applications?

TY
Posted By
testing_you
May 24, 2004
Views
575
Replies
7
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Closed
Hi all,

I was wondering if someone could explain to me in some detail why some of the files display different file sizes depending on how they are being viewed from within Photoshop?

For example, sometimes if I have a file and it is being saved for the web the file might read 8kb from within Photoshop. Now the same file might read 8.62kb if read from within Image Ready or from the computers folders. Sometimes a file that’s been compressed might say it’s being saved at 16kb and then the same exact file will say it’s 15.5kb (just examples to illustrate what I mean) and all without ever leaving photoshop or making any changes or compression or anything to it.

It’s as if the file sizes are all inflated or rough estimates sometimes. I’m curious as to why this happens simply because if I am putting something to a particular website and they might have a file size limit, I would hate to save something and find out it was over and I didn’t know it merely because Photoshop was giving me incorrect file size readings.

Any help is greatly appreciated.

Thank you,

T. Y.
Related Tags
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J
Jim
May 24, 2004
wrote in message
Hi all,

I was wondering if someone could explain to me in some detail why some of
the files display different file sizes depending on how they are being viewed from within Photoshop?
What Photoshop reports is the amount of memory than an image needs.
For example, sometimes if I have a file and it is being saved for the web
the file might read 8kb from within Photoshop. Now the same file might read
8.62kb if read from within Image Ready or from the computers folders.
Sometimes a file that’s been compressed might say it’s being saved at 16kb and then the same exact file will say it’s 15.5kb (just examples to illustrate what I mean) and all without ever leaving photoshop or making any changes or compression or anything to it.
It’s as if the file sizes are all inflated or rough estimates sometimes.
I’m curious as to why this happens simply because if I am putting something to a particular website and they might have a file size limit, I would hate to save something and find out it was over and I didn’t know it merely because Photoshop was giving me incorrect file size readings. The only size that matters is that of the saved file. The Photoshop display shows memory usage not file size. For example, I regularly work on images which require 32mb, but when these images are saved to a jpg file, the file size is 1 or slightly more mb.

Jim
PA
Peter Aitken
May 24, 2004
wrote in message
Hi all,

I was wondering if someone could explain to me in some detail why some of
the files display different file sizes depending on how they are being viewed from within Photoshop?
For example, sometimes if I have a file and it is being saved for the web
the file might read 8kb from within Photoshop. Now the same file might read
8.62kb if read from within Image Ready or from the computers folders.
Sometimes a file that’s been compressed might say it’s being saved at 16kb and then the same exact file will say it’s 15.5kb (just examples to illustrate what I mean) and all without ever leaving photoshop or making any changes or compression or anything to it.
It’s as if the file sizes are all inflated or rough estimates sometimes.
I’m curious as to why this happens simply because if I am putting something to a particular website and they might have a file size limit, I would hate to save something and find out it was over and I didn’t know it merely because Photoshop was giving me incorrect file size readings.
Any help is greatly appreciated.

Thank you,

T. Y.

It’s just rounding – the file is not changing. One app might round the size to the nearest KB, others will not. These small sub-KB diffrences are extremely unlikely to case file size limit problems.

—
Peter Aitken

Remove the crap from my email address before using.
L
LenHewitt
May 24, 2004
a particular website … might have a file size limit, I would hate to
save something and find out it was over <<

The only size that counts in those circumstances is the size on disk, as indicated by Windows Explorer.

The size you see in Save for Web IS an estimate. Until the file is saved the exact degree of compression cannot be known, only estimated. The size you will see indicated on the Photoshop Status Bar is the size of the image IN MEMORY (de-compressed)
TY
testing_you
May 24, 2004
Thank you for your help that was very useful! 🙂
ML
Mike_Logan
May 26, 2004
What is even more confusing (despite the excellent explanation above) is why a file I created was saved as JPG and showed as 121K when viewed in Windows Explorer. I re-opened the image and Saved for Web. I saved the most acceptable result after compression (at about 22%)and re-named it. When viewing in Explorer, it showed this file to be 132K. Can anyone explain THAT ??
L
LenHewitt
May 26, 2004
You probably applied MORE JPEG compression the first time you saved it
ML
Mike_Logan
May 26, 2004
Not too sure about that…. I had created it as a PSD file (as usual) then flattened it and saved as JPEG at the maximum quality (less lossy I think)for my own copy. Just reduced it (compressed it)purely for the web. Still.. as you suggest, PS may have compressed it more in its own way than it does in the Save for Web option. Thanks.

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