fuscobal Posted February 9, 2017 Share Posted February 9, 2017 Hello guys, New to Alamy and was just browsing through the photos to find out most 20 Mpix photos have a very large file size of 50-60MB. How come they are so large in size for the same pixels when my 5D mark II outputs RAW files of just 30MB which then shrink to about 15-20MB for a JPEG (Lightroom or Photoshop set at maximum quality) Link to comment Share on other sites More sharing options...
DJ Myford Posted February 9, 2017 Share Posted February 9, 2017 Alamy originally required uncompressed TIFF files greater than 48MB in size. That was changed to JPEG, which is a compressed file format. The file sizes quoted on the gallery pages are for the uncompressed image (3 Bytes x pixel dimensions) so a 20 MP image will be listed as 60 MB. Link to comment Share on other sites More sharing options...
MDM Posted February 9, 2017 Share Posted February 9, 2017 Alamy originally required uncompressed TIFF files greater than 48MB in size. That was changed to JPEG, which is a compressed file format. The file sizes quoted on the gallery pages are for the uncompressed image (3 Bytes x pixel dimensions) so a 20 MP image will be listed as 60 MB. Sorry for contradicting you but it is important to get the terminology right. The term pixel dimensions is not the same as the size in megapixels as you infer here. Pixel Dimensions is a term used by Adobe in the Image Size dialog in Photoshop and is exactly the same things as Alamy's Uncompressed File Size. So the Pixel Dimensions (Uncompressed File Size ) in MB = 3 x MP size. The megapixel (MP) size is what is shown in Lightroom. The OP is clearly confused (that age old problem) between the Pixel Dimensions (Uncompressed File Size ) and the file size of a JPEG on disk. EDIT: Just to add that Adobe is no longer using the term pixel dimensions in Photoshop CC but did so until quite recently (PSCS6). The image size dialog box now simply states dimensions. Also the pixel dimensions or dimensions depend on whether the file is 8 bit (3xMP) or 16 bit (6xMP) but the MP size does not depend on bit depth. As JPEGS can only be 8 bit, this is not relevant to Alamy submissions. Link to comment Share on other sites More sharing options...
Jon Lewis Posted February 9, 2017 Share Posted February 9, 2017 Dont forget the jpeg compression will also vary the Mb size. with varying complexity in image Link to comment Share on other sites More sharing options...
Betty LaRue Posted February 9, 2017 Share Posted February 9, 2017 Another fact. Alamy, for years, required a file of, was it 48mp? Before saving as a jpeg. At the time until toward the last couple of years of that requirement, no cameras produced a file of that size. I remember when I started as a contributor, I shot a 6 mp Nikon. We had to upsize the images, and that often caused softening and failures. Marginally sharp images just couldn't handle it. Now, if you have a marginally sharp image, you can downsize to 17mp and often that allows it to look sharp enough to pass. Betty Link to comment Share on other sites More sharing options...
MDM Posted February 9, 2017 Share Posted February 9, 2017 Another fact. Alamy, for years, required a file of, was it 48mp? Before saving as a jpeg. At the time until toward the last couple of years of that requirement, no cameras produced a file of that size. I remember when I started as a contributor, I shot a 6 mp Nikon. We had to upsize the images, and that often caused softening and failures. Marginally sharp images just couldn't handle it. Now, if you have a marginally sharp image, you can downsize to 17mp and often that allows it to look sharp enough to pass. Betty You are confusing MB (megabytes) with MP (megapixels). It was 48 MB years ago which is 16 MP and many DSLRs have been producing files that size for a long time now. Also the limit now is 17 MB not 17 MP so a file just less than 6 MP will suffice. Link to comment Share on other sites More sharing options...
Ed Rooney Posted February 9, 2017 Share Posted February 9, 2017 Ouch! My head hurts. Too much tech, too much math! Link to comment Share on other sites More sharing options...
ReeRay Posted February 9, 2017 Share Posted February 9, 2017 Ouch! My head hurts. Too much tech, too much math! I just think > megapixels is length, megabytes is volume Works for my old brain. Link to comment Share on other sites More sharing options...
MDM Posted February 9, 2017 Share Posted February 9, 2017 Ouch! My head hurts. Too much tech, too much math! I just think > megapixels is length, megabytes is volume Works for my old brain. Only if it's an 8-bit cube. Link to comment Share on other sites More sharing options...
NYCat Posted February 9, 2017 Share Posted February 9, 2017 Ouch! My head hurts. Too much tech, too much math! Mine starts to hurt as soon as I see "file size question". Paulette Link to comment Share on other sites More sharing options...
Ed Rooney Posted February 9, 2017 Share Posted February 9, 2017 ReeRay is in a warmer place: less strain on the brain. We're having 14" of snow in NYC today! Hold back on the tech and math, please. Paulette? I don't want to be judgmental, but she hangs out with Polar Bears. Oh oh, I'd better get back on subject. Most of the smaller Sonys I've been using lately feature 20MP, but I've been neurotically downsizing the images to 30-something MB. I don't need to be doing that. Hmm. I think it's payback for when we had to upsize to 48MB. Link to comment Share on other sites More sharing options...
ReeRay Posted February 9, 2017 Share Posted February 9, 2017 Ouch! My head hurts. Too much tech, too much math! I just think > megapixels is length, megabytes is volume Works for my old brain. Only if it's an 8-bit cube. How about > megapixels are measurement, megabytes are content ? Link to comment Share on other sites More sharing options...
ReeRay Posted February 9, 2017 Share Posted February 9, 2017 ReeRay is in a warmer city: less strain on the brain. We're having 14" of snow in NYC today! Hold back on the tech and math, please. Paulette? I don't want to be judgmental, but she hangs out with Polar Bears. Gets boring ya know Ed. Waking up everyday to bright blue skies and T-shirt weather. (Not)???? Link to comment Share on other sites More sharing options...
Ed Rooney Posted February 9, 2017 Share Posted February 9, 2017 ReeRay is in a warmer city: less strain on the brain. We're having 14" of snow in NYC today! Hold back on the tech and math, please. Paulette? I don't want to be judgmental, but she hangs out with Polar Bears.Gets boring ya know Ed. Waking up everyday to bright blue skies and T-shirt weather. (Not) I do know. Very humid. I spent some time in a country two nations to your east. Link to comment Share on other sites More sharing options...
Betty LaRue Posted February 9, 2017 Share Posted February 9, 2017 I well know my mb from my mp, just didn't have my brain engaged. Ed, I saw that the east is getting or got hammered with snow. We're supposed to be around 80 in two days. I'll try to send some of that your way for a big melt down. I'm shooting with 24 mp now, and consider it the perfect mp amount. I didn't much enjoy 36mp. I downsize some of my images, but not all. Link to comment Share on other sites More sharing options...
Niels Quist Posted February 9, 2017 Share Posted February 9, 2017 Hello guys, New to Alamy and was just browsing through the photos to find out most 20 Mpix photos have a very large file size of 50-60MB. How come they are so large in size for the same pixels when my 5D mark II outputs RAW files of just 30MB which then shrink to about 15-20MB for a JPEG (Lightroom or Photoshop set at maximum quality) If you are still in doubt Have a look at this: http://discussion.alamy.com/index.php?/topic/3602-file-size/ Images from your Canon 5DII can be cropped or downsized quite a bit, if you wish. I usually don't, unless I have a very good reason (I often use the same camera model). Link to comment Share on other sites More sharing options...
fuscobal Posted February 11, 2017 Author Share Posted February 11, 2017 Thanks for the answers. There is no confusion for me between MP and MB. My camera has 20MP and the raw files (CR2) have about 30MB on disk. Haven't tried yet to convert the files from raw to tiff but only to jpeg which of course makes them smaller. Reading the other topic posted on a link above, I understand that the 17MB file size limit reffers to the uncompressed format which means the jpeg version can be much smaller. Link to comment Share on other sites More sharing options...
Inchiquin Posted February 12, 2017 Share Posted February 12, 2017 How about > megapixels are measurement, megabytes are content ? Hmm, doesn't really work either because the megapixels are the content. A better analogy is megapixels are the number of words, megabytes are the number of pages. Alan Link to comment Share on other sites More sharing options...
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