I'm having trouble understanding how raw files and jpgs work. I have been shooting with raw files and editing them. Recently I noticed that the original jpg is darker in color that the jpg I saved with the raw file. Then sometimes, after comparing the original jpg with my new one I like parts of it better. Then I copied and pasted parts of the original into my new one. Photoshop told me that the colors did not match, but I did it anyway and it worked. I thought If I saved a jpg copy of my raw file that it would be exactly like the original one. Also the raw file is lighter than the original jpg. Why are they different?
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raw files
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Hoogle
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a jpg is a complete image where as a raw file is not a complete image it has no compression and can only be viewed by specific raw image viewers/ editors.
A jpeg is basically 1 color range from the image and compressed a lot essentially loosing a lot of information arguably though much of that info may not even be noticable. a jpeg will be a fraction of the size of a raw image but then a raw image gives you a lot more editable flexibility in post production.
as an example if you set your camera up to shoot raw and jpeg best settings and then edit it in lightroom or acr you will notice the sliders can only move a small amount on jpegs before you get artifacts and blown out or blackened sections as it cant cope with the details that a raw image can cope with.
Where as a raw image you can bring back a lot of detail which you wouldnt be able to do with a jpeg.
ok a working scenario.
If you take an image of a sky on a summers day that has those lovely fluffy clouds etc you will just see white on a jpeg and no matter how much you under expose it in editing the detail is just not there to restore and make it visible your camera will look at the scene take the picture and save it as it sees it. Where as with a raw image it does not save it in an image format it takes a snap shot of what maybe you can see with your human eye and saves it in a formatbut nit as an image as you would know an image it is more like a personal memory a multi layered psd is a good example. it conatins multiple images of different exposures (ok not really but as an example it sums it up better) and when you edit an image like adjusting exposure and sharpness your scrolling through several images to pick the best 1 for that adjustment. then you move on to something else take the best part from 1 of the many images essentially your taking several parts from many images and making it into 1 image and then you can save that as a jpeg.
Ok really not much true there just a comparison idea to maybe make you see what I mean but really a jpeg and a raw image are the same in the fact they are pictures but pretend a raw image is a 100 layer psd and a jpeg is only 1 layer and that is why a raw image has so much more flexibility
A jpeg is basically 1 color range from the image and compressed a lot essentially loosing a lot of information arguably though much of that info may not even be noticable. a jpeg will be a fraction of the size of a raw image but then a raw image gives you a lot more editable flexibility in post production.
as an example if you set your camera up to shoot raw and jpeg best settings and then edit it in lightroom or acr you will notice the sliders can only move a small amount on jpegs before you get artifacts and blown out or blackened sections as it cant cope with the details that a raw image can cope with.
Where as a raw image you can bring back a lot of detail which you wouldnt be able to do with a jpeg.
ok a working scenario.
If you take an image of a sky on a summers day that has those lovely fluffy clouds etc you will just see white on a jpeg and no matter how much you under expose it in editing the detail is just not there to restore and make it visible your camera will look at the scene take the picture and save it as it sees it. Where as with a raw image it does not save it in an image format it takes a snap shot of what maybe you can see with your human eye and saves it in a formatbut nit as an image as you would know an image it is more like a personal memory a multi layered psd is a good example. it conatins multiple images of different exposures (ok not really but as an example it sums it up better) and when you edit an image like adjusting exposure and sharpness your scrolling through several images to pick the best 1 for that adjustment. then you move on to something else take the best part from 1 of the many images essentially your taking several parts from many images and making it into 1 image and then you can save that as a jpeg.
Ok really not much true there just a comparison idea to maybe make you see what I mean but really a jpeg and a raw image are the same in the fact they are pictures but pretend a raw image is a 100 layer psd and a jpeg is only 1 layer and that is why a raw image has so much more flexibility
agentmoeller
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What he said!!!!!
I think the big takeaway is that jpegs are ALREADY compressed - like someone already edited your photo before you even got it.
Agent
I think the big takeaway is that jpegs are ALREADY compressed - like someone already edited your photo before you even got it.
Agent
Tom Mann
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Here are a few basic articles on RAW files from digital cameras:
http://www.luminous-landscape.com/tutorials/understanding-series/u-raw-files.shtml
http://graphicssoft.about.com/od/glossary/f/raw.htm
http://en.wikipedia.org/wiki/Raw_image_format
I have to say that of all the myriad things that are different between a RAW file and a JPG file, compression would not be the first thing I would put at the top of the list.
The most important difference between the two is simply that the data stored in a raw file is not a bitmap of any sort, by any stretch of the imagination.
First, the raw data has to be de-mosaic'ed before it's in a format that looks like a bit map, ie r11, g11, b11, r12, g12, b12, etc. etc. Before de-mosaicing, the data is a jumble of values with many missing values that must be interpolated into existence.
IMHO, the 2nd and 3rd most importance differences between RAW files and any of the common file formats is that (a) the raw voltages that are linearly proportional to the intensity of each color at each pixel are transformed by a gamma curve to get the luminosity distribution acceptable to the eye, and (b) transform the raw color information into some device independent color space for eventual transformation into the desired output color space (eg, sRGB, ProPhoto, etc.)
Without 1, 2, and 3, above, you don't even have an image that could be compressed. However, once you have 1, 2, and 3, the output of the raw converter could be an uncompressed TIF, a BMP file, or any other common file format.
Tom M
http://www.luminous-landscape.com/tutorials/understanding-series/u-raw-files.shtml
http://graphicssoft.about.com/od/glossary/f/raw.htm
http://en.wikipedia.org/wiki/Raw_image_format
I have to say that of all the myriad things that are different between a RAW file and a JPG file, compression would not be the first thing I would put at the top of the list.
The most important difference between the two is simply that the data stored in a raw file is not a bitmap of any sort, by any stretch of the imagination.
First, the raw data has to be de-mosaic'ed before it's in a format that looks like a bit map, ie r11, g11, b11, r12, g12, b12, etc. etc. Before de-mosaicing, the data is a jumble of values with many missing values that must be interpolated into existence.
IMHO, the 2nd and 3rd most importance differences between RAW files and any of the common file formats is that (a) the raw voltages that are linearly proportional to the intensity of each color at each pixel are transformed by a gamma curve to get the luminosity distribution acceptable to the eye, and (b) transform the raw color information into some device independent color space for eventual transformation into the desired output color space (eg, sRGB, ProPhoto, etc.)
Without 1, 2, and 3, above, you don't even have an image that could be compressed. However, once you have 1, 2, and 3, the output of the raw converter could be an uncompressed TIF, a BMP file, or any other common file format.
Tom M
Tom Mann
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OP: "...I am shooting with a cannon slr rebel. Does that mean that the camera already did some editing on the photo before changing it into a jpg?..."
Yes, the camera has done a huge amount of processing on the raw data to produce a JPG. I described some of these steps in my previous post. In fact, one of the major advantages of having the raw data in your hand is that you don't have to rely on someone else's opinion of what makes a good photo (ie, the camera mfgr). Instead you adjust the parameters in the transformation yourself, exactly as you want.
OP: "...And is it ok to cut and paste some parts from the original jpg into the raw file I'm working on in photoshop? ..."
What you are asking is essentially impossible because (with a few oddball exceptions, ie, Nikon and their Capture NX2 software), RAW files are strictly read-only. You simply can't paste INTO a raw file. However, what you can do is process the raw file for the image in one way, output it to some standard file format (eg, JPG, TIF, PSD), and then you can cut and paste or layer parts of the in-camera JPG into THAT file (ie, but NOT the original RAW file).
HTH,
Tom M
Yes, the camera has done a huge amount of processing on the raw data to produce a JPG. I described some of these steps in my previous post. In fact, one of the major advantages of having the raw data in your hand is that you don't have to rely on someone else's opinion of what makes a good photo (ie, the camera mfgr). Instead you adjust the parameters in the transformation yourself, exactly as you want.
OP: "...And is it ok to cut and paste some parts from the original jpg into the raw file I'm working on in photoshop? ..."
What you are asking is essentially impossible because (with a few oddball exceptions, ie, Nikon and their Capture NX2 software), RAW files are strictly read-only. You simply can't paste INTO a raw file. However, what you can do is process the raw file for the image in one way, output it to some standard file format (eg, JPG, TIF, PSD), and then you can cut and paste or layer parts of the in-camera JPG into THAT file (ie, but NOT the original RAW file).
HTH,
Tom M
Last edited:
Tom Mann
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Finally, to answer the question at the end of your 1st post:
OP: "...Also the raw file is lighter than the original jpg. Why are they different? .."
They almost always are different because the default parameters in whatever raw conversion software you used are almost always going to be somewhat different from the parameters used in the in-camera raw-to-JPG conversion.
Tom M
OP: "...Also the raw file is lighter than the original jpg. Why are they different? .."
They almost always are different because the default parameters in whatever raw conversion software you used are almost always going to be somewhat different from the parameters used in the in-camera raw-to-JPG conversion.
Tom M
Steve
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Basically the JPG is a finished image, processed by your camera.
Things like color, tint, exposure, white point, etc. are locked in.
A raw file is a data file, not a completed image, that can be read by software.
Things like color, tint, exposure, white point, etc. are NOT set and are adjustable with the software.
Some settings like white point are infinitely adjustable, others, like exposure, to a lesser degree.
Things like color, tint, exposure, white point, etc. are locked in.
A raw file is a data file, not a completed image, that can be read by software.
Things like color, tint, exposure, white point, etc. are NOT set and are adjustable with the software.
Some settings like white point are infinitely adjustable, others, like exposure, to a lesser degree.
MikeMc
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OLD SCHOOL THOUGHT.....A RAW file is like your film...the RAW naked truth,what the camera captured. When your camera gives you a jpeg...YOUR CAMERA processed the film and you have a corrected print...RAW file is like shooting a positive(slide)...WYS is WYG ! YES we can take the raw file and convert to a jpeg I prefer to run it thru ACR and PS to get a great result that I view and I tend to save as a Tiff but also a jpeg copy for web / forum use.