Re: [opensuse] Apache2 10.3 - 11.0 website displays differently?
On Wed, January 21, 2009 05:38, Cristian RodrÃguez wrote:
Felix Miata escribió:
The differences in md5sum mainly prove the images are different, not necessarily the page, but the difference between your screenshots is too obvious for md5sums to matter.
Sure, but this is computer science ;) you need a verfication method to know if what your eyes are seeing is true or not, visual perceptions can vary widely and better not to mention the fact browsers, webservers and image processing libraries may have a number of nasty bugs.
If you take two screenshots of a browser window with the address bar visible, in each case with a different url, then of course the image files will be different. That's only logical. Also if you save to a file format that saves the modification date+time in some metadata like EXIF, then your md5sum will be different too. Use GOOD computer science, not computer scientology. :p To compare images, you could use imgcmp: $ imgcmp -f 3111skyline-nemesis.jpg -F 3111skyline-ecstasy.jpg -m rmse 71.544772 71.371629 68.839902 Above zero values means that the images are different. You could also use The Gimp: * load the first image * paste the second image as a the new layer * set layer mode to difference or subtraction. If you get a perfectly pitch black result, then they are identical. Anything else is the difference between the two. In case you see a very dark grey noise, then your images are probably almost identical and the difference can be attributed to a different lossy compression quality. See http://www.flickr.com/photos/25187958@N03/tags/opensuse/ for my results on visually comparing the two screenshots. -- Amedee -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Wednesday 21 January 2009, Amedee Van Gasse wrote:
On Wed, January 21, 2009 05:38, Cristian RodrÃguez wrote:
Felix Miata escribió:
The differences in md5sum mainly prove the images are different, not necessarily the page, but the difference between your screenshots is too obvious for md5sums to matter.
Sure, but this is computer science ;) you need a verfication method to know if what your eyes are seeing is true or not, visual perceptions can vary widely and better not to mention the fact browsers, webservers and image processing libraries may have a number of nasty bugs.
If you take two screenshots of a browser window with the address bar visible, in each case with a different url, then of course the image files will be different. That's only logical. Also if you save to a file format that saves the modification date+time in some metadata like EXIF, then your md5sum will be different too.
Use GOOD computer science, not computer scientology. :p
To compare images, you could use imgcmp: $ imgcmp -f 3111skyline-nemesis.jpg -F 3111skyline-ecstasy.jpg -m rmse 71.544772 71.371629 68.839902
Above zero values means that the images are different.
You could also use The Gimp: * load the first image * paste the second image as a the new layer * set layer mode to difference or subtraction.
If you get a perfectly pitch black result, then they are identical. Anything else is the difference between the two. In case you see a very dark grey noise, then your images are probably almost identical and the difference can be attributed to a different lossy compression quality.
See http://www.flickr.com/photos/25187958@N03/tags/opensuse/ for my results on visually comparing the two screenshots.
-- Amedee
? -- SuSE Linux 10.3-Alpha3. (Linux is like a wigwam - no Gates, no Windows, and an Apache inside.) -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Wed, January 21, 2009 10:47, peter nikolic wrote:
?
I'm afraid you forgot to type a message before sending. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Wednesday 21 January 2009, Amedee Van Gasse wrote:
On Wed, January 21, 2009 10:47, peter nikolic wrote:
?
I'm afraid you forgot to type a message before sending.
intentional -- SuSE Linux 10.3-Alpha3. (Linux is like a wigwam - no Gates, no Windows, and an Apache inside.) -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Amedee Van Gasse wrote:
On Wed, January 21, 2009 10:47, peter nikolic wrote:
?
I'm afraid you forgot to type a message before sending.
Perhaps he's a man of few words. ;-) -- Use OpenOffice.org <http://www.openoffice.org> -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Wednesday 21 January 2009, James Knott wrote:
Perhaps he's a man of few words. ;-)
in some instances you got it ... :-) .. Pete . -- SuSE Linux 10.3-Alpha3. (Linux is like a wigwam - no Gates, no Windows, and an Apache inside.) -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
peter nikolic schreef:
On Wednesday 21 January 2009, James Knott wrote:
Perhaps he's a man of few words. ;-)
in some instances you got it ... :-) ..
I don't get it. Must be a cultural thing. Unlike most of you, I'm not a native English speaker. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Amedee Van Gasse wrote:
peter nikolic schreef:
On Wednesday 21 January 2009, James Knott wrote:
Perhaps he's a man of few words. ;-)
in some instances you got it ... :-) ..
I don't get it. Must be a cultural thing. Unlike most of you, I'm not a native English speaker.
While there are other references, it generally refers to someone who doesn't say much. -- Use OpenOffice.org <http://www.openoffice.org> -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Thursday 22 January 2009, James Knott wrote:
Amedee Van Gasse wrote:
peter nikolic schreef:
On Wednesday 21 January 2009, James Knott wrote:
Perhaps he's a man of few words. ;-)
in some instances you got it ... :-) ..
I don't get it. Must be a cultural thing. Unlike most of you, I'm not a native English speaker.
While there are other references, it generally refers to someone who doesn't say much.
-- Use OpenOffice.org <http://www.openoffice.org>
It's also known as biting ones lip not dishing out what one feels like dishing out :-) Nuff said Pete . -- SuSE Linux 10.3-Alpha3. (Linux is like a wigwam - no Gates, no Windows, and an Apache inside.) -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Thu, January 22, 2009 10:09, peter nikolic wrote:
It's also known as biting ones lip not dishing out what one feels like dishing out :-)
If you don't want to share it on the list, send it to me personally. I can stand the heat. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Thu, January 22, 2009 03:10, James Knott wrote:
Amedee Van Gasse wrote:
peter nikolic schreef:
On Wednesday 21 January 2009, James Knott wrote:
Perhaps he's a man of few words. ;-)
in some instances you got it ... :-) ..
I don't get it. Must be a cultural thing. Unlike most of you, I'm not a native English speaker.
While there are other references, it generally refers to someone who doesn't say much.
I know what the expression means. We use the same expression in Dutch. What I don't understand, is *why*. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Amedee Van Gasse escribió:
If you take two screenshots of a browser window with the address bar visible, in each case with a different url, then of course the image files will be different. That's only logical. Also if you save to a file format that saves the modification date+time in some metadata like EXIF, then your md5sum will be different too.
Does not matter, for the webserver a image file is binary content, different md5sum --> should not expect indentical results, period.
To compare images, you could use imgcmp: $ imgcmp -f 3111skyline-nemesis.jpg -F 3111skyline-ecstasy.jpg -m rmse 71.544772 71.371629 68.839902
Now you are making something very simple to verify unnecessarily complex and bug prone.. -- "We have art in order not to die of the truth" - Friedrich Nietzsche Cristian Rodríguez R. Software Developer Platform/OpenSUSE - Core Services SUSE LINUX Products GmbH Research & Development http://www.opensuse.org/
On Wed, January 21, 2009 14:46, Cristian RodrÃguez wrote:
Amedee Van Gasse escribió:
If you take two screenshots of a browser window with the address bar visible, in each case with a different url, then of course the image files will be different. That's only logical. Also if you save to a file format that saves the modification date+time in some metadata like EXIF, then your md5sum will be different too.
Does not matter, for the webserver a image file is binary content, different md5sum --> should not expect indentical results, period.
No, I'm afraid that you are wrong. Or at least you misunderstood. The two screenshots were taken by the topicstarter to illustrate the differences in what he saw in his browser. The fact that the screenshots were also hosted on the same webserver does not matter. You are simply talking about files. I'm talking about what's inside the files. Take one of the screenshots and convert it to PNG. That will result in a file of about 700 KiB, compared to the original 170 KiB. Your test with md5sum will fail. But the two images are still identical when you do a pixel-by-pixel RGB comparison. Subtract one from the other and you'll get a black image. It's the same when you have an audio fragment in WAV and convert that to FLAC. It's a different media encoding so the files will be different according to md5sum, but the actual sound inside them is identical. Subtract the two soundwaves and you get silence. -- Amedee -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
participants (4)
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Amedee Van Gasse -
Cristian Rodríguez -
James Knott -
peter nikolic