Go Back   Steve's Digicams Forums > Welcome Center > Contact Steve's

Reply
 
Thread Tools Search this Thread
Old Oct 13, 2009, 12:03 PM   #1
Junior Member
 
Join Date: Oct 2009
Posts: 1
Default file sizes

Greetings,

I've just purchased a Lumix FZ35 to replace my previous digital.
I set the camera to 12meg picture size and the jpeg quality to maximum. This is a 12 meg camera but the file size, according to PS, is 32 megs. That's huge for a jpeg and I don't understand how it can be so. Could someone please explain that to me?

Buck
buckduke is offline   Reply With Quote
Sponsored Links
Old Oct 13, 2009, 1:14 PM   #2
Senior Member
 
billy's Avatar
 
Join Date: May 2004
Location: Ohio USA
Posts: 1,733
Default

Are you sure it's not saying 32Mb (MegaBits)?? That's only 4MB (MegaBytes), which sounds about right for a 12-megapixel image.
billy is offline   Reply With Quote
Old Oct 13, 2009, 9:13 PM   #3
Senior Member
 
dwig's Avatar
 
Join Date: Feb 2005
Posts: 133
Default

Quote:
Originally Posted by buckduke View Post
Greetings,

I've just purchased a Lumix FZ35 to replace my previous digital.
I set the camera to 12meg picture size and the jpeg quality to maximum. This is a 12 meg camera but the file size, according to PS, is 32 megs. That's huge for a jpeg and I don't understand how it can be so. Could someone please explain that to me?

Buck
You're a bit sloppy with your terminology which is leading you astray. "Meg" is not a proper term by it self, ever. It means "a million of something" and is somewhat meaningless without specifying what "something" you are talking about. The "12 meg camera" probably means "12 megapixel camera". The 32 meg in PS is going to be "32 megabytes". "Bytes" and "pixels" aren't the same thing.

Where are you seeing the "32 megs" in PS? Unless you are seeing this in a JPEG export dialog its not referring to a JPEG file.

PS can't actually edit a JPEG image, no image editor can. When you open a JPEG in any image editor, including PS, the JPEG is decompressed and converted into a different format for editing. PS, as a convenience to the user, "remembers" that the file was originally a JPEG and will recompress it to JPEG format when you use "Save" automatically without you having to take the extra step select JPEG. It even remembers the compression level and applies the same level of compression (Save as... is provided for when you want the save to be a different format or different compression level). While PS is editing the uncompressed image it will display the size of this uncompressed image. This is likely the 32 megabytes you are seeing. The resaved JPEG will be smaller.
__________________
----
Dwig
dwig is offline   Reply With Quote
Old Oct 14, 2009, 6:05 AM   #4
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Quote:
Originally Posted by buckduke View Post
Greetings,

I've just purchased a Lumix FZ35 to replace my previous digital.
I set the camera to 12meg picture size and the jpeg quality to maximum. This is a 12 meg camera but the file size, according to PS, is 32 megs. That's huge for a jpeg and I don't understand how it can be so. Could someone please explain that to me?

Buck
As dwig mentioned, JPEG files are compressed, and file size will vary by content. When uncompressed for viewing, you will have 3 bytes per pixel being used in memory (one byte for red, one byte for green and one byte for blue). If you multiple 3 bytes by the number of megapixels, you will come up with the open file size (how much space it's taking up in memory after being decompressed by your image editor or viewer).

So, if your image is 12 Megapixels (12 Million Pixels) like you'd have with a resolution setting of 4000 x 3000 pixels (4000 x 3000 = 12 Million), you'll use 36 Million Bytes of memory (12 Million Pixels x 3 Bytes) when it's uncompressed by your image editor for viewing or editing.
JimC is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 1:19 AM.