On Mon, 2010-01-18 at 10:40 +0100, yahvuu wrote:
Philip Rhoades wrote:
It still seems counter intuitive that opening a JPG (even if it is a
photo rather than a computer generated image) and immediately saving it
with 100% quality increases the size by 2.5 . .
That is only non-intuitive
Frank Gore wrote:
But a much better and simpler idea is to just use a
number range from 1..13, similar to photoshop.
I'll take that over to the developer's list.
I disagree, I think Photoshop's way of displaying the JPG compression
slider is ridiculous. You can move the slider back and
Norman Silverstone wrote:
Here is a table that provides an approximate mapping between Photoshop
quality levels and GIMP (actually IJG JPEG library) quality levels:
Adobe Photoshop quality 12 = GIMP quality 98, subsampling 1x1
[..]
wow, i grossly underestimated the influence of the
yahvuu wrote:
Norman Silverstone wrote:
Here is a table that provides an approximate mapping between Photoshop
quality levels and GIMP (actually IJG JPEG library) quality levels:
Adobe Photoshop quality 12 = GIMP quality 98, subsampling 1x1
Sure; subsampling takes groups of 4 x 4
Philip Rhoades wrote:
It still seems counter intuitive that opening a JPG (even if it is a
photo rather than a computer generated image) and immediately saving it
with 100% quality increases the size by 2.5 . .
so you mean the scale should be different? Like
1 .. 10 ... 100 ... 10
Peter,
On 2010-01-18 20:40, yahvuu wrote:
Philip Rhoades wrote:
It still seems counter intuitive that opening a JPG (even if it is a
photo rather than a computer generated image) and immediately saving it
with 100% quality increases the size by 2.5 . .
so you mean the scale should be
Philip Rhoades wrote:
Peter,
On 2010-01-18 20:40, yahvuu wrote:
Philip Rhoades wrote:
It still seems counter intuitive that opening a JPG (even if it is a
photo rather than a computer generated image) and immediately saving it
with 100% quality increases the size by 2.5 . .
so you mean
Philip Rhoades wrote:
Cristi,
On 2010-01-16 06:55, Cristian Secară wrote:
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
snip
But a much better and simpler idea is to just use a
number range from 1..13, similar to photoshop.
I'll take that over to the developer's list.
Is this any help, I came across it a long time ago?
Here is a table that provides an approximate mapping between Photoshop
quality levels
But a much better and simpler idea is to just use a
number range from 1..13, similar to photoshop.
I'll take that over to the developer's list.
I disagree, I think Photoshop's way of displaying the JPG compression
slider is ridiculous. You can move the slider back and forth within a
very wide
On Fri, Jan 15, 2010 at 09:56:40PM +1100, Philip Rhoades wrote:
People,
I found this thread about jpeg very interesting indeed. For this
I thank you all, who asked and who have used his/her spare time to
enlight the audience.
I even think that this thread could be posted in a FAQ/wiki/manual
Cristi,
On 2010-01-16 06:55, Cristian Secară wrote:
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
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):
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
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
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
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
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
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
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
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:
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
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
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 (?)
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
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
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
--
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
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
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 (?)
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
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
[..]
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