RAW, same settings, same camera- why file size differences?
Dec 17, 2018 09:18:40 #
Linda From Maine wrote:
This is interesting to know, and I guess in Gene's haste to be first, he didn't read the opening carefully 
A quick check in my file manager:
Olympus EM10 raw files from 13.2 - 16.9 MB
Panasonic G7 from 16.9 - 17.2 MB
Canon T3i from 21.9 - 30.6 MB
A quick check in my file manager:
Olympus EM10 raw files from 13.2 - 16.9 MB
Panasonic G7 from 16.9 - 17.2 MB
Canon T3i from 21.9 - 30.6 MB
Don't forget that a JPEG image hides inside that RAW file and its size is going to be very dependent upon the content of the image.
Dec 17, 2018 09:20:06 #
JimH123 wrote:
So how do you explain the folks in the thread who have said their raw files are all exactly the same size?Don't forget that a JPEG image hides inside that RAW file and its size is going to be very dependent upon the content of the image.
Dec 17, 2018 09:42:22 #
K
Some companies use compression on raw data. As others said, file size varies with detail. As all raw files contain preview JPEGs, their size varies a little, even when the raw data is not compressed.
With no preview, no compression, they would all be the same size. (Essentially, the sensor data is processed to a bitmap, which is a 3-dimensional array of numbers).
rb61 wrote:
I didn't expect this on RAW files. Copied directly from camera, did not open in an application. In camera processing for RAW?
OMD 10ii
OMD 10ii
Some companies use compression on raw data. As others said, file size varies with detail. As all raw files contain preview JPEGs, their size varies a little, even when the raw data is not compressed.
With no preview, no compression, they would all be the same size. (Essentially, the sensor data is processed to a bitmap, which is a 3-dimensional array of numbers).
Dec 17, 2018 09:57:38 #
The raw file contains more than just the sensor data. Assuming non-compressed sensor data, there are still things that will change in the file even if you have the camera on a tripod taking several shots of the same thing at the same exposure. For one thing the raw file contains a jpg of the image derived from the camera settings. The raw file is compressed (you don't have a choice there) and so due to noise in the sensor data (again, you don't have a choice there -- there is always some noise) the noise will cause differences in the jpg compression so the total size will be slightly different.
The difference will be small for the above scenario: you'll have to look at the file sizes at full precision, not just something like 6.42MBytes.
The difference will be small for the above scenario: you'll have to look at the file sizes at full precision, not just something like 6.42MBytes.
Dec 17, 2018 10:04:12 #
File compression comes broadly in two different flavors: lossy and lossless. JPEG files use a lossy compression technique to produce smaller files by throwing away information that is not very noticeable to the human eye. Raw files are often compressed as well, but since (in theory) they contain all of the image information captured by the camera, these techniques cannot be used. However, the lossless compression schemes (such as are used with .zip files) are still possible and the efficiency of these lossless compression techniques varies with the content - for example, if you capture a solid white wall in RAW, the compressed RAW file is apt to be quite small.
Dec 17, 2018 10:12:35 #
Linda From Maine wrote:
File size is dependent on how much "stuff" is in your image: number of colors and details. For example, a photo that has a lot of blue sky will have a smaller file size (MB) than a garden full of flowers.
(dang, 46 seconds too late to be first)
(dang, 46 seconds too late to be first
)Not sure I understand. For JPEG, I understand that large areas of similar color get compressed more, but I thought RAW stored every pixel without compression? Obviously not as my 5DIV has file sizes ranging from 32 to 45MB.
Can you explain how the RAW file is structured and how it compresses when I thought I was a lossless format?
Thanks
Dec 17, 2018 10:26:19 #
IDguy
Loc: Idaho
Linda From Maine wrote:
So how do you explain the folks in the thread who have said their raw files are all exactly the same size?
They have their file type set as uncompressed.
The default on most cameras is lossless compressed, thus the different file sizes. Many photographers never look at this menu setting.
Dec 17, 2018 10:27:44 #
IDguy wrote:
They have their file type set as uncompressed.
The default on most cameras is lossless compressed, thus the different file sizes. Many photographers never look at this menu setting.
The default on most cameras is lossless compressed, thus the different file sizes. Many photographers never look at this menu setting.
Dec 17, 2018 10:34:43 #
johntaylor333 wrote:
Not sure I understand. For JPEG, I understand that large areas of similar color get compressed more, but I thought RAW stored every pixel without compression? Obviously not as my 5DIV has file sizes ranging from 32 to 45MB.
Can you explain how the RAW file is structured and how it compresses when I thought I was a lossless format?
Thanks
Can you explain how the RAW file is structured and how it compresses when I thought I was a lossless format?
Thanks
Whether or not the RAW file is compressed is a function of the camera. Some only compress, and some give you an option to compress, and perhaps an option to compress as a lossless file or a lossy file. The lossy format throws far less information away then does JPEG, but some mostly unimportant detail can be thrown away.
Each manufacturer has their own way of doing this.
The RAW conversion that is used to read the file knows how to open the file for all supported cameras.
Dec 17, 2018 10:35:36 #
Dikdik
Loc: Winnipeg, Canada
Unless the image is exact, ie. no movement, and the sensor processes it exactly the same, the 'noise' is the same, and there is not one pixel missed or included, they will be slightly different.
Dik
Dik
Dec 17, 2018 10:37:39 #
Dikdik wrote:
Unless the image is exact, ie. no movement, and the sensor processes it exactly the same, the 'noise' is the same, and there is not one pixel missed or included, they will be slightly different.
Dik
Dik
Not true for uncompressed RAW. I suspect that the embedded JPEG will vary.
Dec 17, 2018 10:41:34 #
Dikdik
Loc: Winnipeg, Canada
I disagree... anyone of the items noted, possibly with the exception of noise, can cause the processing of the sensor data to be slightly different. If the RAW data is compressed, the manner of compression, even with lossless, can have a greater impact on the size.
Dik
Dik
Dec 17, 2018 10:45:39 #
It just occurred to me... why does it matter? Who cares? Storage is cheap now.
Photograph an extremely detailed scene, measure the raw file size, and add 10%. That’s a safe figure to use for estimating flash memory card capacities, server requirements, backup...
Photograph an extremely detailed scene, measure the raw file size, and add 10%. That’s a safe figure to use for estimating flash memory card capacities, server requirements, backup...
Dec 17, 2018 10:50:42 #
f8lee wrote:
You must have magic cameras.Not true - raw files are not images, just the data... (show quote)
Dec 17, 2018 10:51:38 #
Linda,
Are all of your camera bodies in uncompressed RAW?
IF they are then, then I'm at a loss to explain the difference in file sizes within the same body.
The sensor has so many pixel sites based on the sensor construction. Each of these sites capture the intensity of light as it comes through its respective Beyer filter as a digital number. Thus the total data size should always be the same as only the number is changing. The number is not in Arabic but in binary thus its always taking up the same amount of files space.
The only other variable that I can think of is bit depth setting. However, I would think that if this is held constant, then the file size should not vary either.
When there is ANY data manipulation, like compression of any sort within the camera, then the total count will vary from one image to the next.
This my understanding which could very easily be all wet.
Are all of your camera bodies in uncompressed RAW?
IF they are then, then I'm at a loss to explain the difference in file sizes within the same body.
The sensor has so many pixel sites based on the sensor construction. Each of these sites capture the intensity of light as it comes through its respective Beyer filter as a digital number. Thus the total data size should always be the same as only the number is changing. The number is not in Arabic but in binary thus its always taking up the same amount of files space.
The only other variable that I can think of is bit depth setting. However, I would think that if this is held constant, then the file size should not vary either.
When there is ANY data manipulation, like compression of any sort within the camera, then the total count will vary from one image to the next.
This my understanding which could very easily be all wet.
Linda From Maine wrote:
This is interesting to know, and I guess in Gene's haste to be first, he didn't read the opening carefully
A quick check in my file manager:
Olympus EM10: orf raw files from 13.2 - 16.9 MB
Panasonic G7: rw2 from 16.9 - 17.2 MB
Canon T3i: cr2 from 21.9 - 30.6 MB
A quick check in my file manager:
Olympus EM10: orf raw files from 13.2 - 16.9 MB
Panasonic G7: rw2 from 16.9 - 17.2 MB
Canon T3i: cr2 from 21.9 - 30.6 MB
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