Hot answers tagged

209

There is a tool called dcraw which reads various RAW file types and extracts pixel data from them — it's actually the original code at the very bottom of a lot of open source and even commercial RAW conversion software. I have a RAW file from my camera, and I've used dcraw in a mode which tells it to create an image using literal, unscaled 16-bit values from ...


67

Once I've a JPEG photograph image file, how can I find out whether it is a RAW file or not? If you have a JPEG file, then it is not a RAW file. RAW isn't a single format, but rather a collective name for image files that contain data straight from the sensor. RAW files need to be processed in order to convert them to more general-purpose image formats like ...


60

Legally, and in typical business practices, what the photographer told you is completely true — she has no obligation to give you RAW files, unless the contract says otherwise. Presumably, the photographer will sell you prints of her work. This is how she makes her living, after all. Kind of harsh to discover after it is too late, but if you wanted ...


53

You could edit your photos with an old burned CRT black and white monitor and it still is the same matter: the additional bits count. Here is a simulation of a 14 bits histogram (A) and an 8-bit one (B). Both are over a blue grid that simulates an 8-bit display or 8bit file format. In B, all the lines coincide. (8-bit format is good enough because is close ...


46

The goal of the imaging engineer has always been to capture with the camera a faithful image of the outside world and present that image in such a way that the observer sees true to life picture. This goal has never been achieved. In fact the best images made today are frail. If this goal were to be achieved, you would need sunglasses to comfortably view an ...


41

Higher bit depths give you more options for editing without losing data. Don't make the mistake of tying the representation of an image with how it is rendered. Editing yields the best quality results when you operate on the representation, where the underlying data has the highest resolution. It just so happens that your monitor provides a lower resolution ...


40

I do offer RAW files for my photos but I don't give them automatically purely because of the size and difficulty to use. A RAW file is substantially larger than even a max quality finished JPEG. Additionally, a RAW file is of no use without a photographer to develop it. It is just raw sensor data and still needs things like color grading and exposure ...


35

In addition to the points Alex S made, you need to consider why they want RAW. There are several possible reasons: Bit depth as Alex S said. JPG suffers from compression artefacts which RAW doesn't. Blown up to exhibtion size these can jump out and ruin a print. Having the RAW file is often used as a proxy for having taken the photo, as RAWs aren't ...


35

You said, this is the information that is captured at first by digital cameras. That is not correct. By themselves, sensors on most digital cameras respond to a broad band of frequencies of light, beyond what humans can see into the infrared and ultraviolet spectrum. Because sensors capture such a broad spectrum of light, they are terrible discriminators ...


35

In my opinion, none of the other answers addresses the obvious misconception in the question: There is no use in converting a JPG (comparatively low quality) to a RAW file (high quality), because you do not gain anything. The reason why people shoot in RAW is that, as others have stated, RAW captures all the sensor data and saves it in a file. JPGs have ...


32

Beyond the very obvious memory card requirement differences between RAW and JPEG images as noted in the question: JPEGs are compressed and typically have much smaller file sizes. For example a RAW file from a Nikon D800 can be 50MB and the JPEG may be a fraction at 10MB. This benefits not only memory card capacity but also editing workflow speed, archival ...


31

This is one of the benefits you get from shooting raw. You can't recover highlight or shadow detail from a JPEG because it has 8 bits of color depth per color component,1 and it's mapped so that the lowest pixel value is interpreted as "black," and the highest is "white." There simply is nothing below black or above white. The creators of JPEG did this ...


28

RAW is not (or minimally) processed image data from camera sensor. JPEG is processed image data. Typically, raw-files from modern cameras have 12-14-bit per pixel which means up to 16384 values (for more details see Michael Clark's comment). JPEG can have only 256 luminance values per RGB channel. This means that jpeg contains much less data than a ...


26

Many digital cameras use lossless compression with raw files. That means the size of raw files from the same camera is somewhat content dependent. The more detail and different colors a scene contains, the larger the file will be. The more homogeneity a scene contains, the smaller the file will be. The degree of the differences will also be governed by ...


26

A picture being worth a thousand spreadsheet cells, here is an histogram of the size of the RAW files from my camera for 2018 (EOS 70D, 20Mpx). Sizes are in 1000's of K (not really MB). For the mathematically inclined: Average: 24538 Median: 24300 Std dev.: 2119


25

No - the aperture is set by the physical blades in the lens when you take the photo; a RAW "image" contains the readings from the sensor when the photo was taken, so there's no way you can go back and modify the light which was captured by the sensor. While it's not as obvious, this is equivalent to asking "Can I modify what the camera was pointing at from a ...


24

A JPEG from a camera is simply a RAW image that has had some additional processing applied. When viewing a RAW image in an image editing program, that program has to go through exactly the same steps as the camera did. If there is any difference in appearance, it is only due to differences in the following (in very rough order from most to least important). ...


23

Unless somebody frivolously renamed a RAW file, it will never have a file name with the .jpg/.jpeg/.jfif extension. Typical extensions for RAW files will be .raw, .arw (Sony), .dng (Android phones etc.), .nef (Nikon), .cr2 (Canon)... A JPEG file will always have the text JFIF somewhere near the start if opened in a text or hex editor, among the hieroglyphs (...


22

But there is nothing objective about perception. If the goal is to attempt to reproduce the perception, the closest will be to set the white balance from a grey card which is not directly lit with the Sun.


22

Is this normal for RAW images? Yes, it is normal. Based on my experience with Canon cameras with different lenses, the RAW image remains uncorrected w.r.t. to the corresponding JPEG. This means that the following corrections set in camera are not applied (and can be applied separately in a RAW conversion program): Colour corrections with picture profiles. ...


20

Raw files don't really store any colors per pixel. They only store a single brightness value per pixel. It is true that with a Bayer mask over each pixel the light is filtered with either a Red, Green, or Blue filter¹ over each pixel well. But there's no hard cutoff where only green light gets through to a green filtered pixel or only red light gets through ...


19

In the absence of real raw files, the JPG is your "raw". Most image editors, including Lightroom, can open or import JPGs. You may choose to save in another format while editing, but do not lose or destroy the original JPGs. Also take care not to save over the original files. It is possible to convert JPGs to DNG. But it's usually used to test and develop ...


17

As you say, white balance is a subjective game. The only way to do this in anyway objectively would be to process your photos in conditions where all the factors affecting subjectivity, i.e. the colour temperature of the ambient light, is the same as when the photo was shot. In my Canon 5D Mk III, for example, this could be done as follows: Shoot the ...


17

From what I understand of your question, you're asking whether a Straight Out Of Camera (SOOC) RAW file should be edited to look "good". The short answer is "Yes, it should go through post-processing". Most (all?) cameras apply their own algorithms to jpg images - in other words, the manufacturer set up the camera to apply what they believe to be ...


17

Going from JPG (which is a lossy format) to any lossless one (like PNG) does not. Going from any format to a lossy one, yes, including JPG to JPG. It could be too little to notice, and using the same compression ratio loses a lot less on the second saving than on the first one, but yes, it is cumulative. But beware... Some image formats store more ...


16

This is essentially the same as Why does my Lightroom preview change after loading? . The RAW file contains a JPEG preview, which reflects the camera's settings and will generally be the same as an in-camera JPEG (although usually in low quality to save space). That's what Darktable is showing you initially. When you go to process the image, Darktable is ...


15

When you shoot monochrome as RAW files, the monochrome setting is just meta-data in the RAW file. The raw data from the sensor is still the same. You will only see the monochrome effect when you view the file in a program that supports the monochrome flag. Obviously what you are using to preview the images doesn't support it. The program from Nikon for ...


15

Nothing makes raw files difficult to manipulate for someone with the right expertise and tools. It's just that there aren't many folks around who have those tools and expertise. The tools needed to manipulate a raw file into a jpeg are much more widespread and well known than those needed to manipulate a raw file into a different raw file. That is probably ...


15

"Better job" is subjective. We certainly get lots of questions like Why does this camera generated JPEG look better than the software generated one? Why do RAW images look worse than JPEGs in editing programs? Why do my RAW pictures look fine in Lightroom preview but become faded when exported? which by their very existence show that many people like the ...


15

Are RAW images by nature slightly blurry prior to processing? If I open them up in Lightroom and zoom into the photo, my photos are not tack sharp but a bit blurry. Once I process, it comes out looking pretty sharp. Wait wait wait — let me stop you right there. When you open up RAW files in Lightroom, you are seeing a processed image. Lightroom does not ...


Only top voted, non community-wiki answers of a minimum length are eligible