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Size of raw files.


franken e2
12 3.3k 4 Wales
7 Aug 2011 6:58AM
When I was out yesterday I took a lot of raw images on my Pentax K-x. When I finished shooting my 8 gig memory card said I still had a fair amount of space left.

When I returned home I loaded the files onto my computer and realised I'd shot 390 plus DNG raw files so the card should show as full?

All the files are showing 4352 by 2868 12.4 megabytes yet the raw files are about 10-11 megabytes each. The instructions say they should be about 20 megabytes?

I've also realised that they've been this size since I purchased the camera new last October.

I've just checked the raw files from my old Pentax K2ooD and they are about 16 megabytes each?

I shoot in DNG format raw (As I did with the 200d) I've just tested the Pentax raw format and the files are still around 10 megabytes!

I know its early in the morning but I'm confused!

Ken

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colin beeley e2
12 1.1k 10 England
7 Aug 2011 9:22AM
i thought photoshop converted raw into dng not the camera ,
franken e2
12 3.3k 4 Wales
7 Aug 2011 9:25AM

Quote:I thought photoshop converted raw into dng not the camera ,


Pentax are the only company that give you the option of shooting in their raw format or Adobe DNG.


Ken
Hi Ken

Clutching at straws, does it have a "small RAW" setting as seen in Canon dSLRs so you capture smaller files rather than the full sized file (hope that makes sense). Smile
HouseMartin e2
5 193 1 England
7 Aug 2011 9:43AM
Just checked with my k-x Ken, and worryingly got an image of about 10.5M (I also shoot dng raw).

So went back through my raw files and it's obviously content dependent as I have a mixture of file sizes from 9M to 18M depending on picture complexity.

I do shoot in sRGB as well and I should imagine shooting in AdodeRGB will increase file size as well - off to try.

Paul
HouseMartin e2
5 193 1 England
7 Aug 2011 9:49AM
Nope, came out the same

Paul
franken e2
12 3.3k 4 Wales
7 Aug 2011 9:55AM
Thanks all for the input so far.
cameracat 11 8.6k 61 Norfolk Island
7 Aug 2011 11:01AM
Barrie is looking in the right direction, Some makers offer " Compression " options for RAW data files, Some don't give you the option ( depends on camera spec and presumed market target) .

Nikon offer on their pro bodies a lossless raw compresion, Though to be honest it hardly saves and space, Big memory cards are so cheap why bother crushing data....Smile

Then there is the " 12bit " Or " 14bit " options on raw data, Plus as mentioned above....Smile


Quote: I have a mixture of file sizes from 9M to 18M depending on picture complexity.


Back to Nikon as an example, My D700 gives me the option to run with 12bit RAW data, Or 14bit, Obviously the 14bit is way better ( I have tested this and the 14bit is superior, No doubt about it....Grin ).

However some if not all the " Non-Pro " Nikon bodies, Do not offer this as an option, Depending on model you get 12 or 14bit RAW data files ( Compressed Lossless ) with no means of changing that, But then why would you when shooting RAW.......Grin

So for those puzzled by their particular camera brand/model......All I can offer is the old " Read the manual " or Read the spec sheet advise, Because its purely down to makers regarding specific models etc etc.......So there is no one particular answer.

One way of checking though is the " Tiff " file size, Look at the open files size of a Fine ( best quality ) JPEG, Lets say that the size is 30Mb, A RAW file converted to an 8bit " TIFF " should be around the same size, Obviously the same RAW file converted to a 16bit TIFF, Should be double at around 60Mb.

Its early on a Sunday, But I hope that helps explain a few mysteries......Grin
User_Removed 10 3.3k 4 United Kingdom
7 Aug 2011 11:20AM
There's clearly some compression going on. I would expect it to be lossless, so for example rather than storing 1200 separate 255 255 255 white pixels as separate bits of data they could be stored as 1 item of data.

I know I'm oversimplifying how lossless compression works but it's just to give the gist.
Ganto e2
8 769 2 Ireland
7 Aug 2011 11:23AM

Quote:All the files are showing 4352 by 2868 12.4 megabytes yet the raw files are about 10-11 megabytes each.


I think there may be some confusion here too. A 4352 x 2868 image would be 12.4 megaPIXELS, which is just the actual pixel count of the image, and does not convert directly to megabytes of data.
franken e2
12 3.3k 4 Wales
7 Aug 2011 12:44PM

Quote:All the files are showing 4352 by 2868 12.4 megabytes yet the raw files are about 10-11 megabytes each.

I think there may be some confusion here too. A 4352 x 2868 image would be 12.4 megaPIXELS, which is just the actual pixel count of the image, and does not convert directly to megabytes of data.



Sorry it was a typing error, you are correct.


Ken
ChrisV e2
8 889 26 United Kingdom
7 Aug 2011 1:28PM

Quote:There's clearly some compression going on. I would expect it to be lossless, so for example rather than storing 1200 separate 255 255 255 white pixels as separate bits of data they could be stored as 1 item of data.

I know I'm oversimplifying how lossless compression works but it's just to give the gist.



I reckon that's just about right.

If the compression is truly lossless [I used to use it when I shot Nikon], surely it's a bit of a bonus?
lobsterboy e2
11 14.3k 13 United Kingdom
7 Aug 2011 2:47PM
DNG uses jpg losless compression so the file should be smaller than raw files. Though there is an oo[tion with DNG to include the original raw format as well which kind of negates the space savings.

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