[Gimp-user] JPG file size increases with saving

2010-01-15 Thread Philip Rhoades
People, I am trying to work out why there is such a large file increase when I edit a file and save it. The background info: Original file (from digital camera) - format, size, depth, geom: JPEG 680590 8 2048x1536 After opening and saving original file with defaults (85% quality):

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Greg Chapman
Hi Philip, On 15 Jan 10 10:56 Philip Rhoades p...@pricom.com.au said: - When saving as JPG with 85% quality am I losing information? Yes! - How can saving as JPG with 100% quality increase information (file size)? It doesn't throw so much info away. It's not actually bigger than the the

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread yahvuu
Hi Philip, Philip Rhoades wrote: - When saving as JPG with 85% quality am I losing information? JPG utilizes lossy compression, which means you'll loose information every time you save as JPG, even at 100% quality setting. That value does not specify the percentage of information stored in

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Philip Rhoades
People, On 2010-01-15 23:33, yahvuu wrote: Hi Philip, Philip Rhoades wrote: - When saving as JPG with 85% quality am I losing information? JPG utilizes lossy compression, which means you'll loose information every time you save as JPG, even at 100% quality setting. That value does not

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread yahvuu
Philip Rhoades wrote: What still doesn't make sense is that if the original file is JPG and one simply opens it and then saves it as another JPG file with 100% quality - you are saying that introduced artifacts are adding about 150% to the file size? (681 KB to 1.618 MB) How could the

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Cristian Secară
On Fri, 15 Jan 2010 21:56:40 +1100, Philip Rhoades wrote: - Why is PNG so inefficient? PNG is not efficient for real life images (ordinary photos). PNG is very efficient for computer generated images (like a snaphot of a program window, or a relatively simple paint, or vector graphics, or some

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Greg Chapman
Hi Philip, On 15 Jan 10 12:53 Philip Rhoades p...@pricom.com.au said: What still doesn't make sense is that if the original file is JPG and one simply opens it and then saves it as another JPG file with 100% quality - you are saying that introduced artifacts are adding about 150% to the

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Paul Hartman
On Fri, Jan 15, 2010 at 4:56 AM, Philip Rhoades p...@pricom.com.au wrote: People, I am trying to work out why there is such a large file increase when I edit a file and save it. The background info: Google the difference between lossy and lossless image compression. Once you understand the

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Akkana Peck
Philip Rhoades writes: What still doesn't make sense is that if the original file is JPG and one simply opens it and then saves it as another JPG file with 100% Because JPEG isn't meant to be saved at 100% quality. The JPEG FAQ, http://www.faqs.org/faqs/jpeg-faq/part1/section-5.html, says:

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Greg Chapman
Hi Philip, On 15 Jan 10 18:27 Philip Rhoades p...@pricom.com.au said: - when the JPG is uncompressed by GIMP into RAM, there is no loss of information (?) No further loss, but the restored image is subject to those averages created when the image was originally compressed. - when GIMP then

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Paul Hartman
On Fri, Jan 15, 2010 at 12:27 PM, Philip Rhoades p...@pricom.com.au wrote: - there was a loss of information when the first JPG was saved in the digital camera memory from the CCD Correct - when the JPG is uncompressed by GIMP into RAM, there is no loss of information (?) Since JPG is not

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Sven Neumann
Hi, On Sat, 2010-01-16 at 05:27 +1100, Philip Rhoades wrote: I guess what is confusing is this: - there was a loss of information when the first JPG was saved in the digital camera memory from the CCD - when the JPG is uncompressed by GIMP into RAM, there is no loss of information (?)

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Bob Meetin
Actually, you get almost no further degradation if you save the image again with the same settings that were used for the first save. The JPEG plug-in even stores information in the image when the image is opened and it will use that information to save it in the best possible way when you

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Cristian Secară
On Fri, 15 Jan 2010 21:56:40 +1100, Philip Rhoades wrote: - When saving as JPG with 85% quality am I losing information? Yes, but still with the same 85% quality you may obtain different results by changing other parameters. Just look at the following example. Note the file size for each, but

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Michael Schumacher
On 15.01.2010 19:59, Greg Chapman wrote: - when GIMP then saves the same image as a new JPG at 100% quality (I would have thought that this meant not losing any more information), You shouldn't take 100% too literally. Especially if the value is not a percentage. Regards, Michael --

Re: [Gimp-user] Color Management Woes

2010-01-15 Thread Milan Knížek
Frank Gore píše v Čt 14. 01. 2010 v 21:35 -0500: Sorry, those were links to the version of the pictures as displayed by Picasa, which has the metadata stripped. The direct download links are as follows: I thought your camera would be very unusual to provide JPEGs w/o metadata... Adobe RGB:

Re: [Gimp-user] Color Management Woes

2010-01-15 Thread Milan Knížek
Frank Gore píše v St 13. 01. 2010 v 18:20 -0500: In any case, like I mentioned in my original post, I specifically have it set to Ask what to do in the Preferences, and it doesn't ask. I agree with you, it is definitely a bug. GIMP should not assume that JPEG is in sRGB colour space when

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread David Hodson
On Fri, 2010-01-15 at 13:32 -0600, Paul Hartman wrote: On Fri, Jan 15, 2010 at 12:27 PM, Philip Rhoades p...@pricom.com.au wrote: - when the JPG is uncompressed by GIMP into RAM, there is no loss of information (?) Since JPG is not lossless, there is always a loss of information. Or more

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Jernej Simončič
On Sat, 16 Jan 2010 10:54:23 +1100, David Hodson wrote: I'm fairly sure this is not true - there is only one way to uncompress a JPG file, so all programs should create the same uncompressed version. Not true - I know that at least different versions of ImageMagick will decompress the same

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Paul Hartman
On Fri, Jan 15, 2010 at 5:54 PM, David Hodson hods...@ozemail.com.au wrote: On Fri, 2010-01-15 at 13:32 -0600, Paul Hartman wrote: On Fri, Jan 15, 2010 at 12:27 PM, Philip Rhoades p...@pricom.com.au wrote: - when the JPG is uncompressed by GIMP into RAM, there is no loss of information (?)

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Bob Long
Philip Rhoades wrote: I am trying to work out why there is such a large file increase when I edit a file and save it. The background info: Original file (from digital camera) - format, size, depth, geom: JPEG 680590 8 2048x1536 [..] After opening, cropping and saving original

Re: [Gimp-user] JPG file size increases with saving

2010-01-15 Thread Philip Rhoades
Bob, On 2010-01-16 11:32, Bob Long wrote: Philip Rhoades wrote: I am trying to work out why there is such a large file increase when I edit a file and save it. The background info: Original file (from digital camera) - format, size, depth, geom: JPEG 680590 8 2048x1536 [..]