Sample Images

In my previous posts you may have seen some sample images which I used to demonstrate certain issues or the result of a certain image processing algorithm. Maybe you wondered where these images come from. Well, it depends on what I am trying to achieve an what I use the images for.

Testing performance of real programs

When I examine how different programs process images, I naturally have to use source images in a special format from an origin that is supported by the program. When I investigate the quality of the demosaicking in a certain program, then it doesn´t help to use a PNG with monitor color space as a test image. In this case I use Raw image files which I typically download from the internet. A good source for such files is dpreview.com. They provide sample images of a huge number of different cameras in Jpeg and Raw format.

Sometimes I also use picture which I took with my own camera. 

Testing performance of self-written algorithms

This is something completely different. For testing my own algorithms I don´t want to use Raw image files which have a custom header and the actual information stored in a weird way. Using such files would require special knowledge about the file format and color reproduction. For this purpose it is much easier to use files which can be easily opened in Matlab and which use the monitor´s color space so you don´t have to mess around with converting colors. One good option for this is the Kodak image set which is used for almost every paper on image processing.

You can download the image suite from http://r0k.us/graphics/kodak/

Another very good source is ARRI. They provide a set of image sequences shot with their professional camera ARRI ALEXA. The files are available in TIFF format in monitor color space and as raw sensor data (Bayer) stored in TIFF files as well. Using TIFF as a container makes it very easy to use these files in your applications. They even share some Matlab code to convert the colors from the sensor´s color space into the monitor´s color space.

Refer to the paper BEYOND THE KODAK IMAGE SET: A NEW REFERENCE SET OF COLOR IMAGE SEQUENCES. The abstract already contains the credentials for ARRI´s FTP server to download the files.