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DPChallenge Forums >> General Discussion >> Why do images change so much when uploaded?
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Showing posts 26 - 44 of 44, (reverse)
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 06/11/2005 10:53:09 AM · #26
Originally posted by stdavidson:
I think if you look you should be able to find a way to assign the color space setting of your image without having to do something funky like changing your printer.

Uh, this is a Windows user, isn't it? sounds like SOP to me ...
 06/11/2005 10:56:51 AM · #27
Originally posted by GeneralE:
Originally posted by stdavidson:
I think if you look you should be able to find a way to assign the color space setting of your image without having to do something funky like changing your printer.

Uh, this is a Windows user, isn't it? sounds like SOP to me ...


That is both funny and a sad truth. I thought the Windows/Mac war was over years ago. LOL
 06/11/2005 10:57:13 AM · #28
Originally posted by stdavidson:
Originally posted by justine:
IrfanView //www.irfanview.com/
Free and does RAW.
If you don't have PSHOP it's the next best.
Also see if you can find a copy of the old Photoshop LE they came free with many printers and you may find someone that has an extra.


Justine... you are pretty with it for someone from Prescott! :) LOL. (Just kidding!)


Mesa ppl. Ha!!
 06/11/2005 11:00:34 AM · #29
Originally posted by justine:
Originally posted by stdavidson:
Originally posted by justine:
IrfanView //www.irfanview.com/
Free and does RAW.
If you don't have PSHOP it's the next best.
Also see if you can find a copy of the old Photoshop LE they came free with many printers and you may find someone that has an extra.


Justine... you are pretty with it for someone from Prescott! :) LOL. (Just kidding!)


Mesa ppl. Ha!!

I look at it this way... all the women I know from outside the PHX metro area think I'm pretty "hot"! LOL.
 06/11/2005 11:07:15 AM · #30
Originally posted by stdavidson:
Originally posted by GeneralE:
Originally posted by stdavidson:
I think if you look you should be able to find a way to assign the color space setting of your image without having to do something funky like changing your printer.

Uh, this is a Windows user, isn't it? sounds like SOP to me ...


That is both funny and a sad truth. I thought the Windows/Mac war was over years ago. LOL

Watch out for that MacTel juggernaut, eh? Personally, I think they are stupid to insist on running the Mac OS only on their own hardware.

If I were in charge I'd port OS X to run on a Pentium and sell Windows users a $129 (or less) crossgrade package, maybe bundled with VirtualPC. People who want the better Mac box will still buy them, just like people still buy Mercedes and Rolls today ...
 06/11/2005 11:09:33 AM · #31
Originally posted by GeneralE:

Maybe it's something that your transfer software is doing.


It is the software that came with the 20D.
 06/11/2005 11:19:10 AM · #32
Another problem solved...just made a phone call and I will have a copy of Photoshop 6 here next week. My sister has it, has never used it, has never even installed it and she is sending it to me. This should be interesting - new camera, new software, same old crappy pictures.
 06/11/2005 11:19:27 AM · #33
Originally posted by GeneralE:
If I were in charge I'd port OS X to run on a Pentium and sell Windows users a $129 (or less) crossgrade package, maybe bundled with VirtualPC. People who want the better Mac box will still buy them, just like people still buy Mercedes and Rolls today ...


Seems to me that I heard recently that is exactly what Apple is going to do. I worked in a cross platform environment developing for both Mac and Windows. We were able to write application source code programs on either a Mac or a Windows platform and it would compile and work in either environment.

The way we were able to do that was by by developing a series of macros that distinguished between being called by a windows or mac machine and would make the proper low level system calls that are different for ach machine. It is actually pretty cool and you don't have to maintain two different sets of source code.
 06/11/2005 11:23:36 AM · #34
No, they are going to use Intel chips in their own machines. But that doesn't mean an off-the-shelf Mac OS will run on any current WinTel box; there must be a lot of programming which involves stuff other than the CPU chip.

Maybe it is their long-term goal, but they certainly haven't stated so publicly.

As I understand it, OS X is a UNIX program, providing the GUI interface to run the other programs. Since UNIX/Linux will run on Pentium boxes, I figured it would be "fairly easy" to port it over, but I am not a programmmer myself. : )

Message edited by author 2005-06-11 11:24:47.
 06/11/2005 11:30:54 AM · #35
Originally posted by Alienyst:
Originally posted by justine:
Originally posted by Alienyst:
Thanks for the suggestions but they all assume someone is using PhotoShop.


What do you use?


PhotoImpact 10.
\

My 20D came with Photoshop Elements 2 bundled. Didn't yours? If so, you could use that.
 06/11/2005 12:04:59 PM · #36
if it sometimes gest slightly bigger then its bein recompressed
 06/11/2005 12:11:46 PM · #37
Originally posted by gusto:
if it sometimes gest slightly bigger then its bein recompressed

From the 'jpegtran' man page:

jpegtran works by rearranging the compressed data (DCT coefficients), without ever fully decoding the image. Therefore, its transformations are lossless: there is no image degradation at all.

(emphasis mine)
 06/11/2005 12:14:36 PM · #38
if an image (EVER) changes in size and is saved again it will get compressed in regards to saving as a jpg. If something is saved and compressed a second time I consider it to be recompressed (.)(.)

you can see below that even in this simple example when an image is enlarged archiving takes place regardless of the final file format selected at the time an image is saved.



Message edited by author 2005-06-11 12:23:00.
 06/11/2005 12:19:44 PM · #39
The point I'm making is that anything the DPC server is doing to your image does not affect the visual characteristics of your image at all. All modifications are lossless from a pixel point of view. You can call it "recompressed" if you want, but that is a misnomer, especially in terms of JPEGs, because JPEG compression is a lossy algorithm. A better term would be transcoded, or even more simply rearranged, since the JPEG compression algorithm is never used by jpegtran (the pixel data is never even fully decoded to recompress it!).

There is a big difference between what jpegtran is doing and loading a JPEG image in an image editor and then re-saving it as a JPEG.

edit to add: I have no idea what your example is trying to show. Image interpolation (resizing) doesn't fit into this discussion at all since DPC does nothing of the sort to challenge entries. If your image is over the 640px limit or larger than 150K, you have to resize / recompress it -- DPC doesn't do it for you. Challenge entries are presented just as they are uploaded by the photographer, pixel for pixel.

Message edited by author 2005-06-11 12:38:23.
 06/11/2005 12:48:40 PM · #40
Originally posted by EddyG:
Challenge entries are presented just as they are uploaded by the photographer, pixel for pixel.

THAT explains my scores!
 06/11/2005 01:05:23 PM · #41
Originally posted by gusto:
if an image (EVER) changes in size and is saved again it will get compressed in regards to saving as a jpg.

I assume this is in response to EddyG saying jpegtran manipulates the image size and yet does not recompress it. If so, to back up what EddyG (and jpegtran) says - it is possible.
 06/11/2005 01:23:21 PM · #42
Originally posted by justine:
IrfanView //www.irfanview.com/
Free and does RAW.
If you don't have PSHOP it's the next best.


I use PaintShop Pro for my image editting, but also have IrfanView. Can someone tell me how to change an image's colourspace with IrfanView as I don't have a clue.

Haven't had any problems with uploaded images, but printouts seem quite different to what I see on the screen.
 06/11/2005 01:30:46 PM · #43
Originally posted by PaulMdx:
Originally posted by gusto:
if an image (EVER) changes in size and is saved again it will get compressed in regards to saving as a jpg.

I assume this is in response to EddyG saying jpegtran manipulates the image size and yet does not recompress it.

No, he's not. The pixel data is "passed through" the process untouched. The FILE SIZE may be changed because of the deletion of extraneous data and re-arrangement of the data on disk, but the mage is not resized.

It's more like removing the wrapper from a candy bar; the insides are the same as what went into the package.
 06/11/2005 01:33:38 PM · #44
Originally posted by GeneralE:
Originally posted by PaulMdx:
I assume this is in response to EddyG saying jpegtran manipulates the image size and yet does not recompress it.

No, he's not. The pixel data is "passed through" the process untouched.

Sorry, I should have said file size.
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