Why do RAW images look worse than JPEGs in editing programs?

Question

I've found that when you load a RAW image into an editing program such as Lightroom/Aperture, the image is usually worse than if you just took the image as JPEG. Now I understand that the camera does some magic during the JPEG conversion. But I'm trying to understand what that "magic" is.

If I'm looking to implement that "magic" myself on the desktop, what kind of settings should I be trying? I find that the RAW files have more extreme contrast. The dark areas for example are way darker than JPEG. Why is this? And what is the best way to fix this?

Answer 1

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).

1. Contrast / Gamma correction

   Gamma correction is applied which converts from the linear values to gamma corrected values as required by digital image files. This correction is not a straight gamma correction; a contrast curve is applied to ensure that highlights and blacks curve off nicely. Some cameras store the camera's contrast setting in the RAW file and some RAW editors can use this; otherwise RAW editors will use an in-built contrast curve. This can create quite a noticeable difference between the in-camera JPEG and an equivalent RAW viewed in an image editor. The contrast curve affects not only the appearance of contrast but also, indirectly, the colour saturation. The great thing about working with a RAW file is that you have full control over the contrast curve applied in software, before lossy operations such as sharpening, noise removal or JPEG compression have to take place.

2. White balance

   White balance correction is applied to correct for different colour temperatures of light sources while taking the picture. Some cameras store the camera's white balance setting in the RAW file and some RAW editors can use this; otherwise RAW editors will guess the correct white balance to apply. This can create quite a noticeable difference between the in-camera JPEG and an equivalent RAW viewed in an image editor. Again, this can also be viewed as a benefit of editing in RAW, in that you are free to re-set the white balance without any lossy artefacts.

3. Sharpening and noise reduction

   An appropriate amount of sharpening and noise reduction are applied to enhance the image and try to suppress annoying noise. There are different sharpening and noise reduction algorithms, and this is a lossy procedure. If this is done in-camera, then you are stuck with whatever sharpening and noise reduction was applied by the camera. A RAW image editor can adjust these values. Differences in the sharpening and noise reduction between that the camera uses and that a RAW image editor uses could create a small difference in the appearance of an image.

4. Colour space conversion

   Red, green and blue in the Bayer filter are not necessarily the same hue as red, green and blue in the standard sRGB colour space. The camera does colour correction to convert the colours into the desired colour space, which is usually sRGB. If you an equivalent image in a RAW image editor, it will also do colour space conversion, but it may use a different colour matrix for the conversion due to the manufacturer of the RAW editing software not having access to the same colour matrices used in the camera. If your RAW editing software is correctly configured, this step should not cause any noticeable difference in the resulting picture. Those who know what to look for (for example, Canon or Adobe's signature colour profiles, which try to enhance skin tones and blues) may be able to notice the difference especially when testing.

5. Demosaicing

   A RAW image does not store colour values for every pixel - instead each value is either a red, green or blue value. However, you need each pixel to have all three colours - red, green and blue - for the final image. Therefore, a demosaicing algorithm has to guess the other two colour parts for each pixels, and it does this based on knowledge of surrounding pixels. There are a variety of different demosaicing algorithms with varying qualities, and it is a lossy process. If this occurs in-camera, then you are stuck with the camera's built-in algorithm. If you use a RAW image editor, it will use its own algorithm. The demosaicing algorithm used is not a huge contributor to overall image quality, but can affect its sharpness, the degree to which it shows aliasing artefacts, and whether it throws away the edges of the image.

6. JPEG compression

   For a JPEG image produced by a camera, the resulting image data is compressed as a JPEG. This is also, obviously, a lossy procedure and can make a difference when comparing it to a RAW image viewed in an image editor, though in most cases the difference shouldn't be noticeable.

In summary, the biggest points of difference between the JPEG produced by the camera and an equivalent RAW produced in an image editor are likely to be caused by:

• Different white balance in both
• Different contrast curve / contrast adjustment in both

Answer 2

Most in-camera jpeg engines increase contrast, saturation, and add some sharpening into the mix. Depending on what camera you use to produce your RAW files and what software you open them with on your computer, sometimes those in-camera settings are also applied to the RAW file when it is displayed. Of course you are not actually viewing the RAW file on your screen; you are almost certainly viewing an 8-bit conversion of that RAW file which is similar to an 8-bit jpeg.

If you are using a Canon camera and open the .cr2 files using Digital Photo Professional (DPP) the in-camera settings selected at the time the image was shot will be applied to the preview image on your screen. Most other manufacturer's in house software does the same thing. Most third party RAW conversion software, such as Lightroom or DxO Optics, do not apply the in camera settings. Some of them will allow you to build a custom profile to apply to each image as it is imported or opened.

The first thing I would recommend regarding the dark areas of your images is to confirm that your monitor is properly calibrated. The best way is to use a calibration tool that reads a test output from your screen and uses bundled software to create a profile for your monitor. A cheaper and less accurate way is to use test patterns to visually adjust your monitor's or video card's settings. Quick Gamma is one such tool. Once you know your monitor is adjusted properly, then you can use the tone curve tool in the RAW convertor of your choice to bring up the shadows.

Answer 3

There's no "magic" it's just that different raw processors have different default behaviors (and different algorithms, etc.).

You can see there's no magic using the camera manufacturer's own raw processor (for example, if your camera is a Canon use DPP) - this should give you exactly the same image has the in-camera processor.

I don't know about Aperture but Lightroom can duplicate the in-camera processing, just scroll down to the "Camera Calibration" section and change the "Profile" from "Adobe Standard" to "Camera Standard" (if you use the camera's "Standard" picture style, otherwise choose the setting that matches the picture style you use in-camera).

Answer 4

A raw file has colors in it that are almost universally outside the small sRGB color space. JPGs are by default sRGB. Raw files look flat because the display is only projecting colors inside the sRGB color space, which have not been converted and containing reassigned colors.