Help for DNTOXYY

PURPOSE:
To generate xyY images (chromaticity x and y and tristimulus Y) from
unknown input multispectral imagery where the scenes contain known
colors. Use this program if the images are not in radiance units or
the bands are outside the visible or of unknown wavelength. If you
know these things then use spectoxyy instead. Once xyY images exist 
they can be converted to rgb for a particular device using xyytospec
or xyy2hdtv.

METHOD:
This method solves for a linear relation between input dn and XYY
tristimulus values. You specify the xyY's and dn's of special colors in the
scene and a solution is made for the C's from the simultaneous
equations:
X(color1)=C1*dn(color1,band1)+C2*dn(color1,band2),...
X(color2)=C1*dn(color2,band1)+C2*dn(color2,band2),...
..ETC..
This is done three times once for X, then Y, and then Z.
Once the C's are known you can substitute any input dn's to derive
the corresponding tristimulus values XYZ. The XYZ's are converted to
xyY's and written out.

All color data are input either after the keyword COLORS or after the
keyword MACBETH. These are the only mechanisms for inputting colors. Each time
you use these keywords the program writes a color calibration file called:
color_calibration.txt. Once this file exists you can cause the program to
read it for processing other images by running dntoxyy without any parameters.
See the example below.

WARNING: If you read a color calibration file your images must retain the same
order and gains as the images from which the file was created.

EXECUTION:

To process images and to create a calibration file:

dntoxyy inp=(band1,band2,...bandn) out=(x,y,Y) colors=(...)
xyy2hdtv inp=(x,y,Y) out=(r,g,b)
or
dntoxyy inp=(band1,band2,...bandn) out=(x,y,Y) macbeth=(...)
xyy2hdtv inp=(x,y,Y) out=(r,g,b)

To process images using an existing calibration file:

dntoxyy inp=(band1,band2,...bandn) out=(x,y,Y)
xyy2hdtv inp=(x,y,Y) out=(r,g,b)


METHOD:
HISTORY:
5-1-2001 J Lorre. 
COGNIZANT PROGRAMMER:  Jean Lorre