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Author Topic: File size  (Read 3447 times)

Offline Sarasocke

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File size
« on: October 04, 2011, 07:43:26 AM »
I'd be interested to hear how large your files are - RAW, JPEG, whatever.
I often hear of enormous files, but other than saving as TIFF, I'm nor clear how one would get there.

My D700 will take RAW and RAW lossless compressed. The RAW files are usually around 24MB the lossless compressed around 14MB.
I'm a bit confused as to how the files can be "lossless" when they are 10MB smaller....  :-\

Converting a 24MB RAW file in ACR at the largest setting (6144 x 4088) at 400 ppi still "only" gives me a JPEG file of around 10 MB.

Maybe I'm just having a blond moment ...


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Offline Hinfrance

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Re: File size
« Reply #1 on: October 04, 2011, 08:51:22 AM »
Those file sizes sound about right. Try opening a RAW file as a 16 bit image, adding a few layers and then saving as a .psd. Guarantee it will be huge, welll over 100mb and quite likely nearer 250mb. Photoshop files are gigantic.
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Offline Jonathan

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Re: File size
« Reply #2 on: October 04, 2011, 10:05:00 AM »
From a D3S (12 MP or so):
14 bit lossless compressed neff about 15-16 MB (never use the 12 bit)
full res normal jpeg SOOC: 3- 4 MB
exported jpegs for magazine etc use (in print): 2MB or so
exported jpegs for blog etc use (on web): 100KB or less

From the H3D:
16 bit compressed raw (3fr): 40 - 45 MB
16 bit raw out of Phocus (fff) 45 - 50 MB

This is why my disks are always full.
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Offline Oldboy

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Re: File size
« Reply #3 on: October 04, 2011, 10:24:34 AM »
I'd be interested to hear how large your files are - RAW, JPEG, whatever.
I often hear of enormous files, but other than saving as TIFF, I'm nor clear how one would get there.


In Photoshop you can increase the size of a file by interpolation, that is adding pixels, to increase the size of the original image. The results depend on the algorithm used. Algorithms are based on a mathematical formula which can be quite involved to produce the best results. For example if you think of a red box made of nine pixels, to increase the size of it, you would add 16 red pixels around the original box, so increasing the size of the box to 25 pixels and by so doing, you have also increased the size of the file. When you do interpolation it degrades the image so you need to apply sharping to make it look less blurry.

As a general rule you can increase the size of an image in Photoshop by six times without degrading an image to much. So, if you increase the image from A3 to A2 it can look fine unless you look at it up close, but generally you would stand further back to view the A2 image than a A3, so this blurriness would be so noticeable.  :tup:


My D700 will take RAW and RAW lossless compressed. The RAW files are usually around 24MB the lossless compressed around 14MB.
I'm a bit confused as to how the files can be "lossless" when they are 10MB smaller....  :-\

Converting a 24MB RAW file in ACR at the largest setting (6144 x 4088) at 400 ppi still "only" gives me a JPEG file of around 10 MB.

Maybe I'm just having a blond moment ...

If you take a landscape shot with a blue sky then, in the original Raw file each pixel of the sky is recorded separately for colour and position in the original Raw file. By using a special algorithm it can record the position of the pixels, but as the colour in the blue sky is the same, it can just record that colour in one place and apply it to all the other pixels in the sky rather than for each individual pixels, so reducing the size of the original file.

The Jpeg file algorithm has greater compression than a Raw file compression, it also throws away information that it doesn't need, so reducing the size of the original file. The problem with this is you have no control of what information it discards so the image is degraded. This is the reason why you shouldn't keep saving a Jpeg file. Having said that you would be hard pressed to notice the difference between a original Raw file and when it's saved as a Jpeg. Hope this answers you questions.  ;D

Offline Hinfrance

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Re: File size
« Reply #4 on: October 04, 2011, 12:43:21 PM »
Serif Photoplus has a lossless jpg file format so you can keep on opening and editing jpgs ad infinitum without loss. Shame no-one else's software understands them ;)
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Offline hevans

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Re: File size
« Reply #5 on: October 04, 2011, 01:21:02 PM »

My D700 will take RAW and RAW lossless compressed. The RAW files are usually around 24MB the lossless compressed around 14MB.
I'm a bit confused as to how the files can be "lossless" when they are 10MB smaller....  :-\

Well, the trick of lossless compression is to find a way to store information in a smaller space with maintaining the capacity to restore it without any change at all.

As an example, if I have the following text:  "AAAAAAAAAAAAAAAAAAAABBBBBBBBBB", it contains 30 characters. However, if I write it as (20A)(10B), i.e. 20 "A" letters followed by 10 "B" characters, then I've effectively compressed the contents to only 10 characters. Knowing the algorithm for re-expanding the compressed version means I can store the original text in 1/3rd the space without losing any information. (This is a simple compression algorithm referred to as run-length encoding).

If you want to know why JPGs are usually "lossy" compression, I can elaborate, but it's a bit more complicated.

Ta.
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Offline Sarasocke

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Re: File size
« Reply #6 on: October 04, 2011, 03:37:04 PM »
Thanks so much for the infos!

I understand why JPEGS are always smaller than RAW files - I always shoot in RAW anyway so I dont' have the problem later in PS, I always have the original.

What I didn't understand was the difference in lossless compressed RAW and the original RAW. If they are of the same quality, why not have only lossless compressed ...
Which version do you guys use?
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Offline Hinfrance

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Re: File size
« Reply #7 on: October 04, 2011, 04:23:25 PM »
Because lossless compression means that the camera has to run the file through the algorithm as it is saved - it takes marginally longer and slows the burst frame rate down. But you'd probably not notice it.

My Pentaxes only save compressed RAW in native format. To write uncompressed RAW I have to switch to .dng. Which I don't :)
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Offline Jonathan

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Re: File size
« Reply #8 on: October 05, 2011, 07:51:18 AM »
There's some techie debate on this across the web.....Nikon's raw compression ain't losless.  Nikon describe it as "visually losless" which presumably means you lose bits you can't see.  Others disagree with the visually bit.
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Offline eysha

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Re: File size
« Reply #9 on: May 17, 2012, 03:00:25 PM »
Johnathan, what does 'it's eysha's round' mean?
I read lots of posts and on some see my name so get confussed  as to why they are there - which is so easy, lol.
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Offline donoreo

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Re: File size
« Reply #10 on: May 17, 2012, 03:02:08 PM »
Johnathan, what does 'it's eysha's round' mean?
I read lots of posts and on some see my name so get confussed  as to why they are there - which is so easy, lol.
In the signatures you can use some code, I see my name, you see yours, etc. 

Offline eysha

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Re: File size
« Reply #11 on: May 17, 2012, 03:26:14 PM »
So my name, for some reason, is in their signatures, lol. Nice of them to remember me, lol. puzzle over i guess
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Offline jinky

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Re: File size
« Reply #12 on: May 17, 2012, 04:38:13 PM »
No your name is not in their signature - the name of the the person who is reading it. So for me it shows jinky rather than your name. Just code in a signature - though if you want to buy us all a round... ;)

Re: raw files with my D700 at largest size my 14 bit lossless raws are all between 13.8-15mb - how come they are so much bigger in Carol`s ACR raw file converter?
« Last Edit: May 17, 2012, 04:41:04 PM by jinky »

Offline donoreo

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Re: File size
« Reply #13 on: May 17, 2012, 04:41:05 PM »
No your name is not in their signature - the name of the the person who is reading it. So for me it shows jinky rather than your name. Just code in a signature - though if you want to buy us all a round... ;)
I thought that is what I said. 

Offline jinky

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Re: File size
« Reply #14 on: May 17, 2012, 04:43:42 PM »
I was commenting on Eysha seeming to think her name was written into other`s signatures just before my post so she did not quite get what you said it seemed.

 

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