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Essential "raw"
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Jan 18, 2018 14:51:56   #
BebuLamar
 
rehess wrote:
He is clearly talking about a "raw" file with a reduced number of pixels - there is no other way to read his restatement!


You didn't read the entire thread. The OP asking for shooting small RAW file and Bill said it's not possible. DTran argued that some RAW are smaller than the other. But Bill said those don't count as he meant the RAW that contains fewer pixels and that's not an option. So he said it's not possible to have fewer pixels in a RAW file.

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Jan 18, 2018 14:54:09   #
MrBob Loc: lookout Mtn. NE Alabama
 
Apaflo wrote:
I did not see even one single reply that got it right!

A RAW file is sensor data encoded using a Bayer Color Filter Array. No more and no less. (It necessarily must be demosaiced to use.)

An image file is an RGB encoded bitmap. (There are other kinds of image files, but DSLR's make RGB bitmaps. All TIFF and JPEG image files are bitmaps, but BW might not be RGB.)

Note that a RAW file actually defines nearly an infinite number of perfectly "correct" image files. A bitmap file defines exactly one and only one image.

Either type of file is made up of just 1's and 0's. Compression has nothing to with it either, nor does noise reduction.
I did not see even one single reply that got it ri... (show quote)


What data is lost from the downsampled RAW file ? If EVERYTHING is retained then what is the purpose of a larger file.... As I said, there is no free lunch and why does the OEM recommend the larger RAW file for IQ ?

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Jan 18, 2018 14:59:01   #
Rongnongno Loc: FL
 
MrBob wrote:
What data is lost from the downsampled RAW file ? If EVERYTHING is retained then what is the purpose of a larger file.... As I said, there is no free lunch and why does the OEM recommend the larger RAW file for IQ ?

Read the link I posted.

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Jan 18, 2018 15:06:44   #
MrBob Loc: lookout Mtn. NE Alabama
 
Rongnongno wrote:
Read the link I posted.


Yes Ron, that is pretty much the same info as I got from a Canon related site on sRAW and mRAW. Possible loss of color accuracy in shadow areas which may affect dynamic range... Even Canon recommends using the largest RAW file available for the best IQ. Be interesting to do a couple test shots but at my level of expertise it prob. would not make any diff.

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Jan 18, 2018 15:18:53   #
Bill_de Loc: US
 
BebuLamar wrote:
I don't know of a camera that save RAW files with fewer pixels than the maximum size. The sensors in most cameras can only capture 1 single color per pixel either R, G or B. Generally there are 2 green pixels per 1 red and 1 blue. After the exposure the camera would read the analog value from each of these pixel and digitize them in either 8, 12 or 14 bit each and some cameras allow option to select this. When you convert an analog value into a digital value you divide it into some number of steps. 8 bit has 256 step, 12 bit has 4096 steps and 14 bit has 16384 steps so you can see more bits can record finer tonal gradation. If the camera use a noise reduction technique mainly for long exposure to subtract the values from a dark noise values from the image values then it can be applied to the RAW data. The RAW converter will then create 3 color values per pixels from 1 color values coming from each of the pixel using the Bayer algorithm or some other improved version.
I don't know of a camera that save RAW files with... (show quote)



Check the Nikon D500, D810, D850.

---

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Jan 18, 2018 15:22:00   #
rehess Loc: South Bend, Indiana, USA
 
BebuLamar wrote:
You didn't read the entire thread. The OP asking for shooting small RAW file and Bill said it's not possible. DTran argued that some RAW are smaller than the other. But Bill said those don't count as he meant the RAW that contains fewer pixels and that's not an option. So he said it's not possible to have fewer pixels in a RAW file.
I always read an entire thread before commenting on it. Where specifically did he say its not possible?? Later on, we had the comment
RRS wrote:
Bill, to answer your question just look at your camera menu and see the size difference in MP between large, medium and small. There is a difference, no free lunch, bigger is better.
{MP is a pixel count}. And you didn't disagree with it either

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Jan 18, 2018 15:27:30   #
Rongnongno Loc: FL
 
I am out, this will run for pages now.

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Jan 18, 2018 18:08:57   #
a6k Loc: Detroit & Sanibel
 
Apaflo wrote:
I did not see even one single reply that got it right!

A RAW file is sensor data encoded using a Bayer Color Filter Array. No more and no less. (It necessarily must be demosaiced to use.)

An image file is an RGB encoded bitmap. (There are other kinds of image files, but DSLR's make RGB bitmaps. All TIFF and JPEG image files are bitmaps, but BW might not be RGB.)

Note that a RAW file actually defines nearly an infinite number of perfectly "correct" image files. A bitmap file defines exactly one and only one image.

Either type of file is made up of just 1's and 0's. Compression has nothing to with it either, nor does noise reduction.
I did not see even one single reply that got it ri... (show quote)


A Sony raw file for most of Sony cameras and perhaps other brands IS compressed. Simple math: the sensor has (example) about 24MP and gives an image that is 6000 x 4000. That is 24,000,000 pixels. Each pixel has three values of 12 or 14 bits. The file contains an embedded JPG and EXIF data as well. The actual file as shown in the OS is about 24 MB. Those are 8-bit bytes. It is not possible to fit all that data into that size file without some kind of compression. There is an option with the a7r3 for uncompressed files and they are much bigger.

I am not trying for a comprehensive explanation. I am just trying to correct the idea that a raw file has no compression.

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Jan 18, 2018 18:51:48   #
BebuLamar
 
rehess wrote:
{MP is a pixel count}. And you didn't disagree with it either


My bad on this point Rehess.

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Jan 18, 2018 18:53:05   #
BebuLamar
 
a6k wrote:
A Sony raw file for most of Sony cameras and perhaps other brands IS compressed. Simple math: the sensor has (example) about 24MP and gives an image that is 6000 x 4000. That is 24,000,000 pixels. Each pixel has three values of 12 or 14 bits. The file contains an embedded JPG and EXIF data as well. The actual file as shown in the OS is about 24 MB. Those are 8-bit bytes. It is not possible to fit all that data into that size file without some kind of compression. There is an option with the a7r3 for uncompressed files and they are much bigger.

I am not trying for a comprehensive explanation. I am just trying to correct the idea that a raw file has no compression.
A Sony raw file for most of Sony cameras and perha... (show quote)


In the RAW file each pixel only has 1 value and not 3.

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Jan 18, 2018 19:20:34   #
Apaflo Loc: Anchorage, Alaska
 
a6k wrote:
A Sony raw file for most of Sony cameras and perhaps other brands IS compressed. Simple math: the sensor has (example) about 24MP and gives an image that is 6000 x 4000. That is 24,000,000 pixels. Each pixel has three values of 12 or 14 bits. The file contains an embedded JPG and EXIF data as well. The actual file as shown in the OS is about 24 MB. Those are 8-bit bytes. It is not possible to fit all that data into that size file without some kind of compression. There is an option with the a7r3 for uncompressed files and they are much bigger.

I am not trying for a comprehensive explanation. I am just trying to correct the idea that a raw file has no compression.
A Sony raw file for most of Sony cameras and perha... (show quote)

Virtually all cameras offer the option of compressing the RAW file, and a few do not offer uncompressed RAW files. But compressed or not does not distinguish what is a RAW file as opposed to an image file, which is specifically what this thread is about.

Note that RAW files (or more correctly the raw sensor data as opposed to the data in an embedded image) do not contain pixel data and do not have three values per sensor location.

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Jan 18, 2018 19:54:40   #
MrBob Loc: lookout Mtn. NE Alabama
 
Apaflo wrote:
Virtually all cameras offer the option of compressing the RAW file, and a few do not offer uncompressed RAW files. But compressed or not does not distinguish what is a RAW file as opposed to an image file, which is specifically what this thread is about.

Note that RAW files (or more correctly the raw sensor data as opposed to the data in an embedded image) do not contain pixel data and do not have three values per sensor location.


I don't think anyone ever questioned the difference between a RAW file of data and an Image file of pixels... The question arose as to whether the different sizes of RAW files available would translate to different IQ's of Image files because of the reduced amt. of RAW data. A 5M RAW file does not contain the same data as a 20M RAW file. Canon even stated that for highest IQ use the largest RAW file available.

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Jan 18, 2018 20:51:17   #
a6k Loc: Detroit & Sanibel
 
BebuLamar wrote:
In the RAW file each pixel only has 1 value and not 3.


I think you are talking about photo sites but a pixel has RGB.

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Jan 18, 2018 21:23:01   #
Apaflo Loc: Anchorage, Alaska
 
MrBob wrote:
I don't think anyone ever questioned the difference between a RAW file of data and an Image file of pixels... The question arose as to whether the different sizes of RAW files available would translate to different IQ's of Image files because of the reduced amt. of RAW data. A 5M RAW file does not contain the same data as a 20M RAW file. Canon even stated that for highest IQ use the largest RAW file available.

The OP was about what makes RAW not an image file.. Several replies totally confused the two, often claiming RAW is just 0's and 1's while an image file, with pixels, is somehow different in that way. None of that has anything to do with the difference between RAW files and image files.

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Jan 19, 2018 05:42:47   #
Peterff Loc: O'er The Hills and Far Away, in Themyscira.
 
Apaflo wrote:
The OP was about what makes RAW not an image file.. Several replies totally confused the two, often claiming RAW is just 0's and 1's while an image file, with pixels, is somehow different in that way. None of that has anything to do with the difference between RAW files and image files.


I find it funny that people get so wrapped around the axle on some of these terminology things. Canon refers to raw image files in its documention. Now clearly a raw file isn't the same as a bit map / pixel level file, but they are both image data files, just in different stages of transformation before they can be seen by a person.

Computer files aren't collections of zeroes and ones either, they are typically electrical, magnetic, or optical binary states. If you pick up a memory device, turn it upside down and shake it like a salt cellar, you do not get little piles of tiny '0 and 1' numerals on your desk.

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