File sizes

W
Posted By
Wolf
Apr 7, 2005
Views
155
Replies
3
Status
Closed
I was emailed a jpg logo, received size was shown as 244kb. Check via properties it shows the same.
However when i open in Photoshop and check in "image size" it shows 10 meg.

What am I missing here, appreciate any advice (well, practically any).
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R
Roy
Apr 7, 2005
"Wolf" wrote in message
I was emailed a jpg logo, received size was shown as 244kb. Check via properties it shows the same.
However when i open in Photoshop and check in "image size" it shows 10 meg.

What am I missing here, appreciate any advice (well, practically any).

It is a Jpeg.

All Jpeg files have some degree of compression applied. When "open" in Ps, or any other program, they will be larger than the "closed" file size.

In Ps the degree of compression can be selected in 12 steps, the higher the number the less compression is applied.

This reduction in size makes it very much quicker to send files by Email, and saves on storage space.

Nothing is for nothing, so there will be a quality loss which is proportional to the amount of compression applied.

The drop in quality may not be visible, but if a Jpeg is opened and edited then re-saved as a Jpeg, the quality loss will be increased, and may well become visible.
It does not take too many savings for the image to become very poor quality.

Roy G
T
Tacit
Apr 7, 2005
In article <Vv75e.2898$>,
"Wolf" wrote:

I was emailed a jpg logo, received size was shown as 244kb. Check via properties it shows the same.
However when i open in Photoshop and check in "image size" it shows 10 meg.
What am I missing here, appreciate any advice (well, practically any).

JPEG images are compressed. When you open a JPEG, it is uncompressed. The file size on disk is the compressed size. the file size in Photoshop is the uncompressed size.

JPEG compression is "lossy." This means that in order to make the file size smaller, the quality of the image is degraded. This degredation is cumulative, permanent, and irreversible.

JPEG was only intended for situations, such as the Web, where file size on disk is important but image quality is not important. It should never be used in cases where image quality is important.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
J
jrzyguy
Apr 9, 2005
yup…i tell all my coworkers to save as either a psd or a tiff…..until they are ready to actualy save as jpg.

"Tacit" wrote in message
In article <Vv75e.2898$>,
"Wolf" wrote:

I was emailed a jpg logo, received size was shown as 244kb. Check via properties it shows the same.
However when i open in Photoshop and check in "image size" it shows 10
meg.
What am I missing here, appreciate any advice (well, practically any).

JPEG images are compressed. When you open a JPEG, it is uncompressed. The file size on disk is the compressed size. the file size in Photoshop is the uncompressed size.

JPEG compression is "lossy." This means that in order to make the file size smaller, the quality of the image is degraded. This degredation is cumulative, permanent, and irreversible.

JPEG was only intended for situations, such as the Web, where file size on disk is important but image quality is not important. It should never be used in cases where image quality is important.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

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