How to create a digital photo

A digital image is formed when an object reflects light, and this light is directed to the sensor under the control of the lens aperture and shutter. This creates an image of the subject on the sensor. You can think of a sensor as a giant chessboard, where each field corresponds to a pixel and can record light information. In fact, the whole chessboard, the sensor surface is only about 30mm². Every light information that hits a field is converted into an electrical pulse by the sensor and stored. Up to this point, no color information has been recorded, but simply lighter or darker points or pixels, depending on the light intensity. This is the RAW-format. In this state, one cannot yet speak of a developed image, but only of collected brightness information of a subject.

Combining RAW and JPEG

For cameras that support RAW, you can set whether to save only RAW files or RAW and JPEG. The dimensions of the image and thus the number of pixels does not differ between JPEG and RAW. But if JPEG is set, the image is already developed and compressed in the camera with the specified settings. Unused information is discarded to minimize the file size. With RAW all information is preserved.

Especially for occasions like weddings, where you take a lot of pictures, the setting “RAW + JEPG” is useful. Therewith, one does not have to develop first 500 RAW photographs but can get an overview by means of the JPEGs and sort out unwanted pictures.

Different camera manufacturers use their own formats and corresponding file extensions. This is how a file at Nikon ends with *.nef, Canon with *.cr2, Sony with *.arw, others with *.raw and so on. The extension *.dng comes from Adobe and is not used directly in a camera, as far as I know. To get an image from a RAW file, it must be converted or imported with a program. The following tools are available:

• CaptureOne
• Adobe Lightroom
• Adobe Photoshop with the Camera RAW Module
• For free: Raw Therapee
• Apple Aperture
• … or own programs of the camera manufacturers

The Advantages of RAW

• The processing of the image remains open and largely independent of the camera settings at the time of recording
• Settings such as sharpening, contrast or white balance can be adjusted later when the image is imported
• A RAW file is also called a “digital negative“. Even if you make changes to an image, you can always access the original RAW file and start over
• One RAW file can be used to create any number of different versions of an image from scratch
• In a dispute over who is the author of an image, this can be clearly proven by showing the RAW file.

The Disadvantages of the RAW Format

• A RAW file can be many times the size of the same JPG file
• Large images require more time to be written to the camera’s memory card. Especially withcontinuous shooting in RAW format, one can quickly reach the limits of the writing speed. The recording is interrupted and the series becomes unusable
• Large pictures need a lot of storage space on the MAC/PC and the transfer to other media needs some patience
• In any case, a RAW file requires a conversion into another format, e.g. to send the file to print or to put it online
• RAW is not readable by every graphics program
• There is no standard format for RAW

JPEG vs. RAW with an example

The JPEG format also has its disadvantages. Thus, the processing of an image may be limited compared to RAW, or not achieve the desired effect. Let’s take as an example of animage that is too bright,which one would like to darken with Photoshop. In tonal value correction, simply move the slider in the histogram to adjust the brightness. For comparison, you first apply the tonal value correction on the RAW file and then copy this tonal value correction layer to the uncompressed JPEG image. In the direct comparison, it is clearly recognizable that some spots on the JPEG are too strongly illuminated and details or structures are difficult to recognize. It is possible to darken the JPEG further, but the colors then deviate markedly from the original appearance. With RAW in this example, one reaches the limits less quickly and gets an easily recognizable image.

This makes it clear that thetransitions between black and white are much more finely graded in RAW.

• RAW with 12Bit = 2 high 12 = 4096 brightness levels per channel
• JPEG with 8Bit = 2 high 8 = 256 brightness levels per channel

Disadvantages of JPEG over RAW

• JPEG is lossy right from the start
• There is less processing scope than with RAW
• The image is already created in the camera with the defined settings such as white balance and all other information about the image is discarded

Advantages of JPEG over RAW

• Requires less space than RAW
• Can be displayed by any graphics program
• Can be used immediately in various media

Proof of copyright with RAW

What is the connection to the topic of image protection? Before an image can be created and processed from RAW data, the data must be converted. However, RAW files are not copy protected. If a picture of you illegally appears, however, you can prove that you are the author by using the RAW data and the META information that it contains. RAW data are therefore considered digital negatives. Whenever possible, make sure that you keep RAW data for important works (despite high storage requirements).