Is raw (nef, cr2, etc) an image file?
Dec 10, 2018 09:58:12 #
JerryOSF
Loc: Bristol, VA
I have seen many claims that jpeg is an image file but raw is not. If I provide a hex printout of one vs the other can anyone easily view either without using a computer? I maintain that all contain image data in a coded form and you must use the proper algorithm to decode this data.
Dec 10, 2018 10:04:13 #
Why is there no pine or apple in pineapple?
What’s the difference between a novel and a book?
Why does a round pizza come in a square box?
Why doesn't Tarzan have a beard?
What’s the difference between a novel and a book?
Why does a round pizza come in a square box?
Why doesn't Tarzan have a beard?
Dec 10, 2018 10:05:25 #
Yes, both files are just DATA.
A JPEG is the data arranged in a particular format for the most common display method.
RAW is ALL the data that the camera creates, unique to the camera manufacturer.
RAW does not have a common display method due to the uniqueness of the data.
Editors/displays that present an image from the RAW data are also done by an algorithm created for that manufacturer, and are different than the algorithm used to present a JPEG image.
Since a JPEG is so common, everyone refers to it as an image file.
A JPEG is the data arranged in a particular format for the most common display method.
RAW is ALL the data that the camera creates, unique to the camera manufacturer.
RAW does not have a common display method due to the uniqueness of the data.
Editors/displays that present an image from the RAW data are also done by an algorithm created for that manufacturer, and are different than the algorithm used to present a JPEG image.
Since a JPEG is so common, everyone refers to it as an image file.
Dec 10, 2018 10:11:29 #
CHG_CANON wrote:
Why is there no pine or apple in pineapple?
What’s the difference between a novel and a book?
Why does a round pizza come in a square box?
Why doesn't Tarzan have a beard?
What’s the difference between a novel and a book?
Why does a round pizza come in a square box?
Why doesn't Tarzan have a beard?
Spot on Paul.
Dec 10, 2018 10:21:55 #
JerryOSF wrote:
I have seen many claims that jpeg is an image file but raw is not. If I provide a hex printout of one vs the other can anyone easily view either without using a computer? I maintain that all contain image data in a coded form and you must use the proper algorithm to decode this data.
This is another pointless argument.
Yes, all "image" files are encoded. Only what we can VIEW, reflected from a print, or displayed in RGB on a monitor, is really an image. Data is just that... data.
The distinction we make about raw files vs all [other] "image file" formats is that a raw file is mostly UNPROCESSED. While it contains one or more preview JPEGs and an EXIF table, it also contains ALL the digitized values from the sensor's photoreceptors. That data is analogous to an exposed color negative film that has not been developed ...or printed. It is pure image potential! We can access any part of it to create pixel values that are transduced into an image for screen or paper.
So when we say a raw file is not an image, we are simply saying that its potential has not been LIMITED by processing. It can be processed in virtually unlimited ways, either to achieve a very accurate semblance of reality, or to achieve a level of artistic interpretation that is unattainable from any other file format.
Dec 10, 2018 10:22:50 #
Dec 10, 2018 10:42:06 #
Both are data files (bits and bytes) but can be displayed as image files when opened with software that can decipher all the bits and bytes.
Dec 10, 2018 10:50:35 #
bpulv
Loc: Buena Park, CA
burkphoto wrote:
This is another pointless argument. br br Yes, al... (show quote)
As usual Bill, you have hit the nail on the head.
Dec 10, 2018 10:55:42 #
I just posted this explanation on another thread:
Think of a digital imaging chip as a matrix of rows and columns, where an array of 6000 by 4000 would yield 24 million "dots" or pixels (picture elements). A raw file is the stream of data that comes from the sensor. With a few exceptions (Leica's monochrome, Foveon) ALL digital sensors, from that new Hasselblad to your smart phone camera, work as follows: while they too have a matrix of dots (called photo sites), each of those photo sites is covered with a colored filter that is either Red, Green or Blue. This is because the sensor chip itself is natively "color blind", each photo site can only register how many photons have struck it when exposed. The pattern of those colored filters (called the Bayer pattern) is R-G-G-B (for upper left, upper right,, lower left, lower right) - and there are twice as many green filters as there are red or blue because the human eye is more sensitive to green. Fuji's X-Trans chip uses a different pattern, but the concept is the same.
When an exposure is made, the data captured by the imaging chip is a bunch of values that represent how much light hit each photo site - and those measurements are all based on the light that made it through those filters. As a thought experiment, imagine a subject that was only pure blue - the photo sites with red and green filters above them would not register anything! Lots of black gaps in that file, eh?
So a raw file first needs to be rejiggered to become a true image file, where each image pixel has a stated RGB value. On the raw file, each spot has only an R OR a B OR a G value, but they are not blended. That process is called de-mosaicing, and the output of the process is the resultant image. Obviously there are a lot of calculations required to do this, but that's what the computer built into the camera (or phone) does. Cameras that only output JPEG do in fact create raw files to start with (there is no other option) but they quickly do the calculations and discard the raw file when the JPEG is created.
So, unlike a JPEG or TIF etc. file, the computer processing a raw file must interpret what actual color should appear at a given pixel, based on the readings made from the surrounding photo sites. There is no absolute lookup table, as there is for image file RGB values, to decide what color purple a given spot should be if one adjacent red reading was 500, another from the blue filter was 644 and yet another from a green filter spot was 42, or whatever. For those who say "yeah but you need a computer to interpret" any digital file!” I say that is actually incorrect - where a JPG specifies that RGB value (and leaves it to the hardware drivers and gear to not screw it up) the various demosaicing programs can actually result in different outputs from the same original raw file. Apple includes demosaicing software in OS X, but DxO, Phase One's Capture One, Adobe and others (including the camera manufacturers themselves) all have their own demosaicing software. While different software won't completely change the look of a given image, the subtle tonalities can well be different if you take an image and process it with C1 and compare that to the same raw file run through Adobe Lightroom.
By the bye, since you CANNOT see a raw image what you are looking at (on the back of the camera when you chimp, or on a computer screen) is a demosaiced image that has been interpreted by a computer, be it in the camera or on your desktop.
While of course everything digital is recorded as a stream of 0's and 1's, a JPEG or TIF etc image file prescribes a specific RGB value for each spot of the image - no interpretation is required, just a value from a lookup table. Raw files are not images until their individual photo site readings are blended and merged by demosaic software to ascertain what specific RGB value to apply to a given 'dot'. There is no standard lookup table to do this (unlike with a JPEG, where it's pretty straightforward), which is why different raw processing engines can come up with (slightly) different colors from the same original raw file. For instance, there are those who say that Capture One Pro dies a better job than, say Adobe in processing raw image files...this is why.
Think of a digital imaging chip as a matrix of rows and columns, where an array of 6000 by 4000 would yield 24 million "dots" or pixels (picture elements). A raw file is the stream of data that comes from the sensor. With a few exceptions (Leica's monochrome, Foveon) ALL digital sensors, from that new Hasselblad to your smart phone camera, work as follows: while they too have a matrix of dots (called photo sites), each of those photo sites is covered with a colored filter that is either Red, Green or Blue. This is because the sensor chip itself is natively "color blind", each photo site can only register how many photons have struck it when exposed. The pattern of those colored filters (called the Bayer pattern) is R-G-G-B (for upper left, upper right,, lower left, lower right) - and there are twice as many green filters as there are red or blue because the human eye is more sensitive to green. Fuji's X-Trans chip uses a different pattern, but the concept is the same.
When an exposure is made, the data captured by the imaging chip is a bunch of values that represent how much light hit each photo site - and those measurements are all based on the light that made it through those filters. As a thought experiment, imagine a subject that was only pure blue - the photo sites with red and green filters above them would not register anything! Lots of black gaps in that file, eh?
So a raw file first needs to be rejiggered to become a true image file, where each image pixel has a stated RGB value. On the raw file, each spot has only an R OR a B OR a G value, but they are not blended. That process is called de-mosaicing, and the output of the process is the resultant image. Obviously there are a lot of calculations required to do this, but that's what the computer built into the camera (or phone) does. Cameras that only output JPEG do in fact create raw files to start with (there is no other option) but they quickly do the calculations and discard the raw file when the JPEG is created.
So, unlike a JPEG or TIF etc. file, the computer processing a raw file must interpret what actual color should appear at a given pixel, based on the readings made from the surrounding photo sites. There is no absolute lookup table, as there is for image file RGB values, to decide what color purple a given spot should be if one adjacent red reading was 500, another from the blue filter was 644 and yet another from a green filter spot was 42, or whatever. For those who say "yeah but you need a computer to interpret" any digital file!” I say that is actually incorrect - where a JPG specifies that RGB value (and leaves it to the hardware drivers and gear to not screw it up) the various demosaicing programs can actually result in different outputs from the same original raw file. Apple includes demosaicing software in OS X, but DxO, Phase One's Capture One, Adobe and others (including the camera manufacturers themselves) all have their own demosaicing software. While different software won't completely change the look of a given image, the subtle tonalities can well be different if you take an image and process it with C1 and compare that to the same raw file run through Adobe Lightroom.
By the bye, since you CANNOT see a raw image what you are looking at (on the back of the camera when you chimp, or on a computer screen) is a demosaiced image that has been interpreted by a computer, be it in the camera or on your desktop.
While of course everything digital is recorded as a stream of 0's and 1's, a JPEG or TIF etc image file prescribes a specific RGB value for each spot of the image - no interpretation is required, just a value from a lookup table. Raw files are not images until their individual photo site readings are blended and merged by demosaic software to ascertain what specific RGB value to apply to a given 'dot'. There is no standard lookup table to do this (unlike with a JPEG, where it's pretty straightforward), which is why different raw processing engines can come up with (slightly) different colors from the same original raw file. For instance, there are those who say that Capture One Pro dies a better job than, say Adobe in processing raw image files...this is why.
Dec 10, 2018 11:27:18 #
Dec 10, 2018 12:04:58 #
W9OD wrote:
Every day, I wake up and ponder all of these😜.
Well good for you! Knowledge is power!
But ignorance is bliss, so I can't say which is better...
Dec 10, 2018 12:53:46 #
Some people have waaaaay too much time on their hands . . .
Dec 10, 2018 13:28:37 #
Dec 10, 2018 15:35:28 #
JerryOSF wrote:
I have seen many claims that jpeg is an image file but raw is not. If I provide a hex printout of one vs the other can anyone easily view either without using a computer? I maintain that all contain image data in a coded form and you must use the proper algorithm to decode this data.
They are exactly the same to a Blind Man
Dec 11, 2018 06:35:40 #
CHG_CANON wrote:
Why is there no pine or apple in pineapple?
What’s the difference between a novel and a book?
Why does a round pizza come in a square box?
Why doesn't Tarzan have a beard?
What’s the difference between a novel and a book?
Why does a round pizza come in a square box?
Why doesn't Tarzan have a beard?
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