fact or fiction?

"Commonly used programs such as Adobe
Photoshop write additional information into JPG file that isn’t needed for correctly displaying the picture."

is this true?

Yes.

what additional info would that be?

You know how when you save a Photoshop file, the icon looks like a tiny version of the image? That icon is written into the file.

So is the preview that you see when you click on the file in Photoshop’s Open dialog. Photoshop also writes a color profile into the picture, if you have color management enabled. If a JPEG comes from a digital camera that embeds EXIF data into the image, then Photoshop writes that EXIF data into the file.

All this information–icon, preview, and so on–is not necessary for reading the JPEG.

If you want to save a JPEG that does not have this extra information in it, use the Save for Web command, or use the Preferences command to instruct Photoshop not to include this information.

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A human being called Tacit
typed the following stuff which he/she expects us to read

You know how when you save a Photoshop file, the icon looks like a tiny

version

of the image? That icon is written into the file.

So is the preview that you see when you click on the file in Photoshop’s

Open

dialog. Photoshop also writes a color profile into the picture, if you have color management enabled. If a JPEG comes from a digital camera that embeds EXIF data into the image, then Photoshop writes that EXIF data into the

file.

All this information–icon, preview, and so on–is not necessary for reading the JPEG.

If you want to save a JPEG that does not have this extra information in it,

use

the Save for Web command, or use the Preferences command to instruct

Photoshop

not to include this information.

aha, the world is one smarter guy richer now. thanx!