Usually the dimming of a light source is done by changing the voltage of the power supply.

As described in our TechNote „Linearization“, it is an important task to linearize digital images before any calculations can be done.

Cameras that address experienced users, such as D-SLR and system cameras, normally offer a RAW-Mode. In this mode, the camera puts files onto the memory device, that are called “Raw”-Files, as they contain the pure data which was obtained from the sensor and has not been processed.

Our products are used all over the world by a huge number of talented engineers. They help them to produce better cameras and to get their customers satisfied. A lot of these engineers work on products that have not been revealed to the public yet and they have to take care that no one will know about the product before official release.

If you are in a hurry or just not interested in some background information, here is the essence for you – HDTV (Rec. 709) and sRGB share the same primary chromaticities, but they have different transfer functions.

The color rendering index (CRI) is a value which expresses the degree of reproducing color of a sample to a reference illuminant. In various fields of application in video and still imaging it is necessary to reproduce colored targets. The color of an object is determined by three properties: the illuminant, the object’s reflectance and the observer. Regarding to the ability of color reproduction of different illuminants, we want to explain the meaning of the color rendering index in this TechNote.

Using a Siemens star ist a great way to measure the MTF of a camera system. We use this method for years and see that it is much more robust against image enhancement and other influences than a slanted edge.

In this TechNote we would like to present three ways to convert a raw (bit-stream) image into a conventional image file format. In this case we define a raw image as a series of bits. The .raw file contains only information about the image pixel values, there’s no header and no additional information included (in contrast to the camera raw files e.g. CR2, NEF, ARW, ORF, RAF etc.).

There are a couple of different methods out there to measure "the" SFR (Spatial Frequency Response) of a digital imaging system. The problem is, that you might get different result using different methods.

All D-SLRs and a lot of “Prosumer”-Compact cameras have a “RAW-Mode”. Unfortunately, the image files have a proprietary file format and the manufacturers would like the user to use their software in order to convert from RAW to an image file format like JPEG or TIFF. To get access to the data within the RAW-files, we use an open source software called dcraw by Dave Coffin.

TE241, TE264 or TE259 can be used to measure the opto electronic conversion function. The TE259 is a modified OECF chart following ISO 14524 and ISO 15739 using a horizontal gray scale instead of a circular one. We do highly recommend to have these standards available during measurements to be able to crosscheck the settings of your measurement setup with the standards.

In the times of film based cameras the sensitivity of the film was characteristic for the film type selected by the photographer. This film type was produced to a specified sensitivity. Film processing had limited influence in varying the sensitivity and also the characteristic curve of the film. To get the best results the images were exposed assuming that the average scene has an overall reflection of 18% of the incident light.