Image-size of jpeg's

[vvizard]

I was wondering if there's any tool that can take an jpeg-image, and output it in the filesize you specify. *NOTE* This has to be on-the-byte correct, and baseline-encoded, so all decoders can open it again. Also, it need to take the stored exif-information into account, and preserve it. Might be a daunting task, but does anyone know if there exist such a tool?

[Conk]

Doe's "save for web" not do that in photoshop? I doubt the exif being saved but I'd think it does save file size to the byte.

[vvizard]

It got to do both. This is a challenge from the police-department of whether their "system" can be spoofed or not. So I added some foreign elements into the pictur, and saved it back with the original EXIF intact. That was what I was supposed to do. Then I get "Filesize doesn't match".. DOH! Like I was ever told it should? :wink: So now I need to try finding a way of compressing an image "just the right way" so it's correct-to-the-byte in filesize. Of course that would have to preserve the exif. Cause if it doesn't, then I'll need to add it again, and then the filesize will not match again..

[meow]

What if you compress to the exact size minus the size of the EXIF and then inject the exif afterwards? (For instance BreezeBrowser will do this - don't know about PS).

[vvizard]

Ok, I could take a look at them. Don't use photoshop or breeze, but if they can compress with "on-the-byte" perfection, I'll check them out.

[meow]

Sorry, I meant that BB can inject the exif. Compression isn't its thing, me thinks.

[atleypnorth]

why not just make the jpeg smaller than required and then pad out the filesize with dummy data in the exif? probably easier then trying to guess the compression to use

[vvizard]

That might sound as a good idea.. Image-viewers just display "known" EXIF-fields don't they? So if there's suddenly an EXIF-field named "__BOGUS__" with 500KB of data, the viewers will just ignore it? If so, this was a perfect solution. Got to hit the bed now, but I'll look into it in the morning =D

[Scottes]

Take a look at Steganography.

[cprevost]

I don't know exactly what you are trying to achieve, but didn't canon come out with some software that detects digital editing.


Canon today announced the latest version of its Data Verification Kit, the DVK-E2 kit is designed to deliver validation of an unmodified original image from a single camera body. This kit is aimed at law enforcement, insurance, news and other such agencies and can detect single bit discrepancy in modification of an image since it was taken. The new kit is much smaller than the old and uses a unique SM (secure mobile) card which is the same size as a Secure Digital card. The card reader connects to a computer USB port (only Windows 2000/XP compatible at the moment).
Link
http://www.dpreview.com/news/0401/04012903canondvke2.asp

[Andy_T]

Hmmm ... if that results in parking wardens getting equipped with the 1DII or 1Ds (because these cameras support the new feature) than that's surely going to add to the appeal of the job :lol:

Best regards,
Andy

[MrChevy]

Seems as if some reading this thread don't seem to understand what vvizard said.

The camera "makes" the file a certain way. The police software opens the photo and can "see" that the photo is UN-modified. ie EXACTLY as it came from the camera. THOSE photos CAN be used in a court of law.

Change even ONE pixel in the photo and the photo "blueprint" is corrupted then and the police software will show a big MODIFIED regarding the photo, and it is no good for evidence.

vvizard is working with the police in trying to "make" a photo that the police software will "think" is UN-modified. Then they will have to work on their software some more to catch "those" kinds of photos.

It seems he hasn't succeeded yet :)