Basic question about RAW images

somberg

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My understanding is that jpeg images have been processed by my camera and RAW images have not. Why, then, when I have my camera record both and then display them on the screen, do they look identical? I am guessing that whatever program I use to display the images has done some processing on the RAW images, but it (if that is the explanation) it is curious that the camera and the computer software made equivalent copies.
 

Danmunro_nz

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Both the raw file and jpeg will look the same until you make adjustments to the raw file.

With raw you can change white balance, exposure, saturation, contrast, sharpening etc.

Where as jpeg you do not have so much room to correct these things as it is the final image.

Raw provides a non destructive way of editing after the fact, where as jpeg does not. Hope that makes sense. I'm no real expert but that's my understanding.
 

HughGuessWho

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Both the raw file and jpeg will look the same until you make adjustments to the raw file.
.

Not true. The OP stated it correctly. Jpegs are processed in camera to your camera manufactures taste. Raw files have had zero processing. Therefore, they will seldom look anything alike straight out of the camera. Some raw editing software, such as Lightroom, by default will add a touch of sharpening and some noise reduction when the file is opened, unless that is turned off in options. Otherwise, you must do all of the corrections yourself.
 

JoeCool76

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When the camera records the RAW file it also embeds a processed JPG preview. This preview is what you see on the LCD after taking the picture. Some programs simply display the same preview instead of developing the RAW file. The camera manufacturer's software may also read all of the camera settings from the RAW file and develop the photo exactly the same way the camera would.
 

SCraig

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The RAW file contains the sensor data without any manipulation by the camera. All of the camera settings are ignored, HOWEVER they are also written to the RAW file so that the data can be reconstructed using those camera settings if desired. They ARE the settings used to generate the JPEG thumbnail that is also part f the RAW file and they CAN be used by any software as initial settings for editing the file. Many times editor options will include "As Shot" or "In Camera" or something as one of the settings that can be used, and those values come from the RAW file. Something must be used for the default values so it might as well be those.

My guess is that your editor is doing that, it is using the camera values to initially manipulate the data so that what you see as a representation of the RAW data is very similar to what a JPEG looks like. The fact is that they SHOULD look similar since they both used the same camera settings at that point.
 

480sparky

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Both the raw file and jpeg will look the same until you make adjustments to the raw file.
.

Not true. ..........


You're both right.

The 'correct' answer depends on your software and the settings within it.

Some software applies the camera settings recorded and uses them during the demosiacing process. If so, the raw and JPEG images will look the same. Other softwares DO NOT apply the settings during demosaicing, and therefor the images will look different.
 

KmH

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The OP may be looking at a JPEG thumbnail of the Raw file and not the Raw file itself, because the OP doesn't say what application he is looking at the Raw files with.

Raw files have had zero processing.
Only until the Raw image data is processed so it can be seen as an image instead of as a file of 1's and 0's.

To make the Raw file an image, a fair amount of processing has to be done, from demosaicing (color interpolation), because the image sensor in a digital camera cannot record color, to adding a non-linear gamma curve to the file because the luminosity values the image sensor recorded linearly don't look like the world people see with non-linear eyes.

The RAW file contains the sensor data without any manipulation by the camera.
The camera does quite a bit of manipulation to the data the image sensor recorded. The analog voltages the image sensor pixels generate have to be amplified, and then the voltage each pixel generated has to be converted to a 12-bit or 14-bit digital number.
That voltage amplification and A/D conversion is done by the camera.
Sensor data is also manipulated by the Bayer Array and Anti-Aliasing filter that is in front of the image sensor.
 
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somberg

somberg

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Wow, guess it wasn't such a basic question. Thanks to all for their input.
 

HughGuessWho

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The OP may be looking at a JPEG thumbnail of the Raw file and not the Raw file itself, because the OP doesn't say what application he is looking at the Raw files with.

Only until the Raw image data is processed so it can be seen as an image instead of as a file of 1's and 0's.

To make the Raw file an image, a fair amount of processing has to be done, from demosaicing (color interpolation), because the image sensor in a digital camera cannot record color, to adding a non-linear gamma curve to the file because the luminosity values the image sensor recorded linearly don't look like the world people see with non-linear eyes.

.

I was referring to POST processing. Obviously a raw file has to be converted from 1 and 0's to be viewed, amazingly, just like a jpeg does. An unprocessed, (as in no color correction, no sharpening, no contrast adjustments) raw file looks absolutely nothing like a jpeg with all of the above adjustments applied. Just because you editing software is set to automatically apply presets to all images, does not change that fact, as I believe was the OP's question.
 

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Raw conversion demosaicing and gamma curve application is POST processing.

That's why each Raw conversion application produces a somewhat different looking image.
 

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