.TH "pfsglview" 1
.SH NAME
pfsglview \- Viewer for high-dynamic range images in pfs format
.SH SYNOPSIS
.B pfsglview
[--h] [--v]
.SH DESCRIPTION
pfsview is a OpenGL/GLUT application for viewing high-dynamic range images. It
expects pfs stream on the standard input and displays the frames in
that stream one by one.

.SH DYNAMIC RANGE WINDOW
To show high-dynamic range data on a low-dynamic range monitor,
pfsglview uses concept of a dynamic range window. The dynamic range
window is the highest and lowest value that should be mapped to black
and white pixel. Values above or below the window are clipped (see
clipping methods below). The dynamic range window is displayed in
pfsglview as a blue area on the dynamic range scale (second toolbox from
the top). The window can be moved, shrunk and expended using a mouse
or a keyboard.

.SH ZOOMING AND PANNING
To zoom image, the mouse can be dragged in vertical direction with the left button pressed. 
Pressing [space] button or pressing left mouse button above the statistic window (left-bottom corner) changes from 
zooming to panning modes and vice versa. To pan image, the mouse can be dragged in vertical 
and horizontal directions with the left button pressed. 

.SH POPUP MENU OPTIONS
.TP
.B Zoom reset
Set default zoom parameters.
.TP
.B Zoom in
Increase image (mouse dragging with left button pressed).
.TP
.B Zoom out
Decrease image (mouse dragging with left button pressed).
.TP 
.B Increase exposure
Move dynamic range window into higher luminance values.
.TP
.B Decrease exposure
Move dynamic range window into lover luminance values.
.TP
.B Extend dynamic range
Extend dynamic range window.
.TP
.B Shrink dynamic range
Shrink dynamic range window
.TP
.B Low dynamic range
Set dynamic range window to <-1,1> range (log scale).
.TP
.B Fit to dynamic range
Set dynamic range windo to minimum and maximum luminance of a given image.
.TP
.B Choose channel
Change image data channel.
.TP
.B Mapping method
Change mapping method (see below for details).
.TP
.B Next frame
Display next image from the pipe.
.TP
.B Previous frame
Display previous image from the pipe.
.TP
.B Histogram
Switch on/off histogram window.
.TP
.B Info
Switch on/off info window.
.TP
.B Save&Quit
Send the visible LDR image (8-bits) to stdout and quit pfsglview.


.SH MAPPING METHODS

High-dynamic range data are usually better visualized using non-linear
scale, for example a logarithmic or a power function. pfsglview offers
several such scales, shown in \fIpopup\fR menu. Gray-scale values for
each mapping method are computed by the formulas:

\fBLINEAR\fR: y = (x-min)/(max-min)

\fBGAMMA\fR: y = [ (x-min)/(max-min) ]^gamma

\fBLOGARITHMIC\fR: y = (log10(x)-log10(min))/(log10(max)-log10(min))

where \fIy\fR is the gray-scale value after mapping, \fIx\fR
is an input HDR value, \fImin\fR and \fImax\fR are lower and upper bounds
of the dynamic range window.

.SH EXAMPLES
.TP
pfsin memorial.hdr | pfsglview 
See the memorial image.
.TP
pfsin memorial.hdr | pfsglview | pfsout memorial.jpg
See the memorial image and save the clipped (8-bits) version to memorial.jpg (\fISave&Quit\fR option from popup menu should be activated).

.SH "SEE ALSO"
.BR pfsin (1)

Please report bugs and comments to Radoslaw Mantiuk <radoslaw.mantiuk@gmail.com>.