wduncan
newbie
Reged: 03/03/2008
Posts: 8
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I am interested in sending in some digital images on CD to the Gallery section. I note that the requirement is 12MB uncompressed minimum for RGB. My question is, how do I know what the uncompressed file size is? My understanding of JPEG is that files are compressed by up to 70%. Therefore, if I have a compressed JPEG of 2MB, does this mean that the uncompressed size is 6MB?
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T Sargeant
Jessies' Finest *
Reged: 01/08/2004
Posts: 1866
Loc: Reading, Berkshire
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Someone will correct me if I'm wrong, but I believe that if you open them up in Photoshop, you should be able to see what the size is...
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Tom
CRIPN
"When the only tool you own is a hammer, every problem begins to resemble a nail!"
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TheFatControlleR
L'éminence Grise, Devil's Advocate & AP Fanboy!
Reged: 24/04/2001
Posts: 10841
Loc: In A Glass Darkly
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Quote:
Someone will correct me if I'm wrong, but I believe that if you open them up in Photoshop, you should be able to see what the size is...
In Photoshop that is the case (bottom left of the window), not sure about other editors.
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TheFatControlleR
And so, my fellow Benchists: ask not what your bench can do for you - ask what you can do for your bench... Ben Chism
Live fat, die young, and leave a self-basting corpse...
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ermintrude
Hinkypuff
Reged: 30/06/2003
Posts: 12344
Loc: London, UK
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This is all true - but why is it in Feedback & Suggestions 
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Further, longer, higher, older...
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mark_jacobs
AP Art Editor
Reged: 07/08/2001
Posts: 1329
Loc: Santa Monica Boulevard 8585, a...
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Another way to say this would be 2480x1754 pixels
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Bawbee
Stick'in wi'it
Reged: 06/05/2000
Posts: 6765
Loc: Dundee, Scotland, UK
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Quote:
This is all true - but why is it in Feedback & Suggestions
Because TFC moved it here, OK!? 
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Bawbee BSRIPN
"Don't judge each day by the harvest you reap but by the seeds that you plant."
Bawbee Louis Stevenson 1850-1894
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4477
Loc: Really Here In Name Only
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Quote:
My understanding of JPEG is that files are compressed by up to 70%. Therefore, if I have a compressed JPEG of 2MB, does this mean that the uncompressed size is 6MB?
I can show you examples of images which can be compressed by a lot more than 70% during conversion to JPEG and still look fine. I can show you examples of images which have been compressed by less than 50% and look terrible as a consequence.
You can't extrapolate the uncompressed size of an image file from the size of a JPEG made from it.
You can't even obtain the uncompressed file size from the image height and width in pixels without knowing the colour depth ... not even Photoshop will tell you as PS will be working in a 8 16 or 32 bit colour depth conversion.
If the Gallery wants files to be a minimum size in pixels, it should say so - not confuse everyone by quoting an "uncompressed" size in megabytes. I guess the requirement is around 2400 x 1600 pixels (11,520,000 bytes uncompressed at 8 bit colour depth), minimum, if so that is what should be stated.
Of course even that needs qualifying according to the aspect ratio... nothing is ever simple, but trying to simplify too much just confuses people 
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mark_jacobs
AP Art Editor
Reged: 07/08/2001
Posts: 1329
Loc: Santa Monica Boulevard 8585, a...
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Quote:
…I guess the requirement is around 2400 x 1600 pixels… if so that is what should be stated…
I thought I had 
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mark_jacobs
AP Art Editor
Reged: 07/08/2001
Posts: 1329
Loc: Santa Monica Boulevard 8585, a...
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Quote:
This is all true - but why is it in Feedback & Suggestions
So that you won't be able to find it when out looking for cafetiere inserts and copies of AP
I imagine that the real reason is that it's been asked as an AP specific question rather than a general one. As such here, although not perfect, is appropriate …now where is that piece of string that needs measuring…
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ermintrude
Hinkypuff
Reged: 30/06/2003
Posts: 12344
Loc: London, UK
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Quote:
Quote:
This is all true - but why is it in Feedback & Suggestions
So that you won't be able to find it when out looking for cafetiere inserts and copies of AP
Ah oui, mais... pourquoi would I want a copy of AP? 
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Further, longer, higher, older...
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Burgy
Grateful not to have one
Reged: 13/04/2001
Posts: 5188
Loc: This far, from beating 7 shade...
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Quote:
You can't even obtain the uncompressed file size from the image height and width in pixels without knowing the colour depth
Seeing as Jpeg doesn't support anything other than 8-bit, it is rather academic or even irrelevent.
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Cheers
Burgy BSRIPN, BSc, DSO and Bar (now open 24/7).
it's not what you've got, its who you do it to
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Lounge Lizard
Old Wrinkly
Reged: 17/01/2004
Posts: 17885
Loc: Cambridge, Cambridgeshire
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Quote:
Quote:
Quote:
This is all true - but why is it in Feedback & Suggestions
So that you won't be able to find it when out looking for cafetiere inserts and copies of AP
Ah oui, mais... pourquoi would I want a copy of AP?
Pour vous battre de la tête pour demander les questions bêtes. D'accord?
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Lounge Lizard
Success is the ability to go from one failure to another with no loss of enthusiasm.
Winston Churchill
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ermintrude
Hinkypuff
Reged: 30/06/2003
Posts: 12344
Loc: London, UK
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Quote:
Quote:
Quote:
Quote:
This is all true - but why is it in Feedback & Suggestions
So that you won't be able to find it when out looking for cafetiere inserts and copies of AP
Ah oui, mais... pourquoi would I want a copy of AP?
Pour vous battre de la tête pour demander les questions bêtes. D'accord?
Vous ressemblez mon petit ami 
Monsieur Jacobs a déjà collé un bâton vers le haut de mon cul
(C'est une plaisanterie, Monsieur Jacobs, notez le smiley )
Regardez! :  
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Further, longer, higher, older...
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Lounge Lizard
Old Wrinkly
Reged: 17/01/2004
Posts: 17885
Loc: Cambridge, Cambridgeshire
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Quote:
Monsieur Jacobs a déjà collé un bâton vers le haut de mon cul
I don't think we explore this avenue any further! 
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Lounge Lizard
Success is the ability to go from one failure to another with no loss of enthusiasm.
Winston Churchill
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ermintrude
Hinkypuff
Reged: 30/06/2003
Posts: 12344
Loc: London, UK
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Quote:
Quote:
Monsieur Jacobs a déjà collé un bâton vers le haut de mon cul
I don't think we explore this avenue any further!
Pourquoi, vous n'aimez pas mon cul?
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Further, longer, higher, older...
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wduncan
newbie
Reged: 03/03/2008
Posts: 8
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Thanks to everyone and I do now see that the file size in MB is quoted in the bottom left of photoshop. Having looked at a few of my images, it would appear that as a very loose rule of thumb, the size in megabytes tends to be roughly three times the size in megapixels.
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