LDR Tonemapping

    This tonemapper produces a desatured and blured version of the image which is combine with each RGB channel using a function. This process can be applied more than one time and each time the effect is applied is called a 'stage'. After this, the user can desaturate the portions of the image where the initial value was either very low or very high. After this step, there is an optional unsharp mask to enhance the details of the processed image.
    The user can view the original image, the processed image or both images same time (original is in the left and processed in the right).
    User can pan the image by dragging with the mouse and can zoom by using the scroll wheel.

Tonemapping parameters

Usually, the parameters are not linear: on lower settings they grow very slow, but on the higher settings they grows very fast. This produces more 'natural' behaving settings.For each stage this parameters are available:

• enabled - if the current tonemapping stage is enabled
• power - how strong the effect is applied
• blur - how strong the image is blured before combining with the original image with the tonemapping function

The next parameters are global for the whole effect:

• function - this is the function which combines the original RGB chanels with the desaturated blured image. This function used on each of the tonemapping stage. It can linear or power. Basicaly, these function increase the value where both the original and blurred image's value are low and do the opposite on high values
• stretch contrast - this stretch the contrast of the original image. This is applied before the tonemapping process
• high saturation and low saturation - Usually the (perceived) saturation is increased. The user can choose to lower the saturation on original highlight and shadows from the image with these parameters
• fast mode - there are available two ways to do the tonemapping: using a very fast algorithm, which might produce artifacts on the image or a more precise algorithm, which is slower

Unsharp parameters

• U.M. enabled - enable the unsharp mask filter
• U.M. power - the strenght of the unsharp mask
• U.M. blur - how much the image is blurred into the unsharp mask filter
• U.M. threshold - this avoids increasing the noise of the unsharp mask filter

View

• preview - if checked the processed image is shown, else the original image is displayed
• histogram - shows the histogram of the displayed image
• show - "image" - show one image'; "half" shows the original image in the left and the processed in the right. The next two modes f(x) and f(x,y) shows the tonemapping function and is more used in developing this program; "x" here represents the original channel value and "y" represents the value of the blurred image. f(x) shows the function as a line for every possible input values, the other parameter (blurred, or 'y') is set by clicking of the mouse on the screen. The f(x,y) mode shows the function for every possible combination of input channel value and 'blurred' value.

Menus

File menu

• Open image... - open an image from file. You can load many file types, if you check to show all files. 
• Save image... - saves the processed image to the file
• Batch process images... - select many files from a directory and select the output directory. After this, all images are processed with the current setting. This is very useful to process a time-lapse sequence of images. 
• Reset parameters - all tonemapping parameters are set to default
• Open parameters... - loads the tonemapping parameters from a file
• Save parameters... - write the current parameters to a file
• Exit - close the program