pfmViewer

pfmViewer is a tool for viewoing .pfm files, where you can make adjustment to the image. To be more specific, we give a demo here.

For an image with intensity $I[\mathbf{x}]$, the code employs the following formula $\left( \frac{I[\mathbf{x}] - \text{offset}}{\text{divider}} \right)^{1/\gamma}$

For this demo, you need the memorial.pfm image from Paul Debevec webpage.

Opening the image

This is like any image opening procedure. The curve fields are: The "subtract" field for the $\text{offset}$ variable; the "divider by" field for the $\text{divider}$ variable; and the "gamma" field for the $\gamma$ variable in the equation above. After opening the "memorial.pfm" image, you get

Employ Gamma Correction

The image is in the linear rgb color space. To display it properly on the screen, you need to employ Gamma correction; assuming gamma is 2.4, $\gamma=2.4$, we get

Exploring Darker Regions

There are many dark regions in the image, and one may wish to see these more clearly. In this case, we need to amplify these values. This can be achieved by adjusting the "divide by:" field, as shown in

Exploring Brighter Regions

One may also be interested in exploring brighter regions. In this case, the "divide by:" field can be set to values larger than 1.0; this can be seen in the following image.

The rest is self-explanatory.