What exactly is happening to a Raw photo when it becomes a JPEG and what about Raw photos are so preferable for photo editing
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A lot of people have mentioned that jpeg is “lossy compression”. This means that there is a lot less information than in the raw image.
What other people have not mentioned yet is why jpeg looks so good _despite_ so much information being discarded.
Your eyes are pretty good, but they aren’t perfect. You will have experienced this when looking at something which is far away, like a mountain. You don’t feel like you are missing out on anything, but to see distant details you know that you will need binoculars.
What jpeg does is remove the information that you would only perceive in an image if you zoomed into it. If you don’t zoom in, you will not know it is missing.
If you are a professional photographer, you want this information (that you can’t normally see) because the processing you might want to do could bring that information into the perceptible range.
You can try it yourself. Take an image and save it as a JPEG with extreme compression, and then zoom into it. You will see the artefacts introduced by the lossy encoding.
Saving an image as a jpeg throws away most of the information that the image originally had, in order to make the file size smaller. A RAW image file has all of the information that the camera can provide.
If you want to edit the image later, to tweak the colors or remove redeye or whatever, you want to use the RAW version that has all of the information. If you edit (and then resave) jpegs, you’re losing _more_ of what little of the original information was still in the jpeg. Do this too many times and your picture becomes horribly blocky and blurry like an old meme that’s been passed around too many times.
Saving an image as a jpeg throws away most of the information that the image originally had, in order to make the file size smaller. A RAW image file has all of the information that the camera can provide.
If you want to edit the image later, to tweak the colors or remove redeye or whatever, you want to use the RAW version that has all of the information. If you edit (and then resave) jpegs, you’re losing _more_ of what little of the original information was still in the jpeg. Do this too many times and your picture becomes horribly blocky and blurry like an old meme that’s been passed around too many times.
You lose some data when converting to a JPEG. The raw photo has all of the data points that make up the picture. The JPEG can be a much smaller file by guessing the pixels between the ones that it saves as part of the format.
Using an analogy I used from another post with a similar question:
So every digital camera takes all the data (color/light/white balance/exposure) in and interprets it a little differently. You shoot a photo and let’s say, Apple, has decided how it should look. Sort of like giving a chef ingredients and they decide how it should taste. That’s a jpeg.
With RAW, the camera takes all the data in and instead of deciding for you how it interprets it, it just gives you the data and you can use an image editor or RAW processor to decide how it looks. Sort of like the chef giving you the ingredients back and saying “make it yourself”
It gives you more control over the image because it’s just…raw data. With a jpeg, you can edit and make tweaks to the color or exposure, etc. But it’s more limited. Like if you tried to take the chef’s creation and modify the flavor. You could change a it a bit but it’s not going to stretch very far.
So RAW can be helpful in tricky lighting situations where the shadows might be too dark or the highlights might be too light. It gives you more latitude to try to save those details later. Or if you are shooting in fluorescent light the color balance might look funky. You have a greater ability to correct that before the quality starts to deteriorate.
You might notice if you open a RAW image in a RAW editor, it might appear flat or too dark or too light. That’s because the camera didn’t make the decisions about what the contrast should be or how green the green should be, etc. Now that being said, most image viewers/editors will show you an embedded jpeg version as the preview. So it might look fine until you go to edit it. So RAW images require a little more work to make them look how you want them to.
Some cameras have good JPEGS that people are perfectly happy with. For example, most people find that Fujifilm cameras have very good straight out of camera jpegs. I also shoot a Fuji camera and I shoot RAW+JPEG so I can use the jpeg if I’m happy with it. Maybe tweak it a little bit. Or I can use the RAW if I want more control.
Hope that makes sense!
You lose some data when converting to a JPEG. The raw photo has all of the data points that make up the picture. The JPEG can be a much smaller file by guessing the pixels between the ones that it saves as part of the format.
Using an analogy I used from another post with a similar question:
So every digital camera takes all the data (color/light/white balance/exposure) in and interprets it a little differently. You shoot a photo and let’s say, Apple, has decided how it should look. Sort of like giving a chef ingredients and they decide how it should taste. That’s a jpeg.
With RAW, the camera takes all the data in and instead of deciding for you how it interprets it, it just gives you the data and you can use an image editor or RAW processor to decide how it looks. Sort of like the chef giving you the ingredients back and saying “make it yourself”
It gives you more control over the image because it’s just…raw data. With a jpeg, you can edit and make tweaks to the color or exposure, etc. But it’s more limited. Like if you tried to take the chef’s creation and modify the flavor. You could change a it a bit but it’s not going to stretch very far.
So RAW can be helpful in tricky lighting situations where the shadows might be too dark or the highlights might be too light. It gives you more latitude to try to save those details later. Or if you are shooting in fluorescent light the color balance might look funky. You have a greater ability to correct that before the quality starts to deteriorate.
You might notice if you open a RAW image in a RAW editor, it might appear flat or too dark or too light. That’s because the camera didn’t make the decisions about what the contrast should be or how green the green should be, etc. Now that being said, most image viewers/editors will show you an embedded jpeg version as the preview. So it might look fine until you go to edit it. So RAW images require a little more work to make them look how you want them to.
Some cameras have good JPEGS that people are perfectly happy with. For example, most people find that Fujifilm cameras have very good straight out of camera jpegs. I also shoot a Fuji camera and I shoot RAW+JPEG so I can use the jpeg if I’m happy with it. Maybe tweak it a little bit. Or I can use the RAW if I want more control.
Hope that makes sense!
You lose some data when converting to a JPEG. The raw photo has all of the data points that make up the picture. The JPEG can be a much smaller file by guessing the pixels between the ones that it saves as part of the format.
Using an analogy I used from another post with a similar question:
So every digital camera takes all the data (color/light/white balance/exposure) in and interprets it a little differently. You shoot a photo and let’s say, Apple, has decided how it should look. Sort of like giving a chef ingredients and they decide how it should taste. That’s a jpeg.
With RAW, the camera takes all the data in and instead of deciding for you how it interprets it, it just gives you the data and you can use an image editor or RAW processor to decide how it looks. Sort of like the chef giving you the ingredients back and saying “make it yourself”
It gives you more control over the image because it’s just…raw data. With a jpeg, you can edit and make tweaks to the color or exposure, etc. But it’s more limited. Like if you tried to take the chef’s creation and modify the flavor. You could change a it a bit but it’s not going to stretch very far.
So RAW can be helpful in tricky lighting situations where the shadows might be too dark or the highlights might be too light. It gives you more latitude to try to save those details later. Or if you are shooting in fluorescent light the color balance might look funky. You have a greater ability to correct that before the quality starts to deteriorate.
You might notice if you open a RAW image in a RAW editor, it might appear flat or too dark or too light. That’s because the camera didn’t make the decisions about what the contrast should be or how green the green should be, etc. Now that being said, most image viewers/editors will show you an embedded jpeg version as the preview. So it might look fine until you go to edit it. So RAW images require a little more work to make them look how you want them to.
Some cameras have good JPEGS that people are perfectly happy with. For example, most people find that Fujifilm cameras have very good straight out of camera jpegs. I also shoot a Fuji camera and I shoot RAW+JPEG so I can use the jpeg if I’m happy with it. Maybe tweak it a little bit. Or I can use the RAW if I want more control.
Hope that makes sense!
Others have explained JPEG is a compression technique. Here’s my ELI5 attempt to explain compression in general:
Let’s say you have an image made up of 8 pixels. Left to right the pixels are:
“Bright red, black, black, dark grey, darker grey, black, dark grey, red.”
That’s the “raw” format: each pixel gets an exact color value. But, it takes up a lot of space since we have to list the exact color for every pixel.
We could compress this by converting it to:
“Bright red, 2 black, dark grey, darker grey, black, dark grey, red.”
This is called “lossless” compression because we’ve shortened it slightly, but no information was lost. But, shades of dark grey and black are pretty close. If we wanted to shorten it more, we could do:
“Bright red, 6 black, red.”
This is a lot shorter, but we’ve lost some detail. Instead of seeing the subtle variations in the dark colors, it’s all just black now. This is called “lossy” compression. JPEG is a type of lossy compression.
You can see that JPEG is fine for most situations, but if you want to edit a photo, you’re better off starting with the version that has all of the information and detail.
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