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 2048x1

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

2010-01-15 Thread David Hodson
On Fri, 2010-01-15 at 18:07 -0600, Paul Hartman wrote: > On Fri, Jan 15, 2010 at 5:54 PM, David Hodson wrote: > > On Fri, 2010-01-15 at 13:32 -0600, Paul Hartman wrote: > >> [...] the same JPG can be interpreted differently by > >> different software, so opening it in GIMP might look different th

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 or

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 wrote: > On Fri, 2010-01-15 at 13:32 -0600, Paul Hartman wrote: >> On Fri, Jan 15, 2010 at 12:27 PM, Philip Rhoades wrote: > >> > - when the JPG is uncompressed by GIMP into RAM, there is no loss of >> > information (?) >> >> Since JPG is not lossless

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 JP

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 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 specifical

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 whe

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 R

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, Michae

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 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 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 > informati

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 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 lossless, there

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 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 saves the same

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 Philip Rhoades
People, On 2010-01-16 00:11, yahvuu wrote: > 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

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 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 fundamental

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 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 file size? (681 K

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 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 compr

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

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 th

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 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 raw data (i.e. to

[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): JP