A question about the LAB_Channel module
from United States  [214 posts]
12 years

I need to use the L, a and b values from the LAB_Channel module as inputs to an artificial neural network.  As I understand it, the a and b values can take on both negative and positive values.  Does the RoboRealm API return the negative values if I do a getImage() after applying the LAB_Channel module?  Putting it another way, how can I get the negative values as well as the positive values?


Anonymous 12 years
The a and b values are scaled to a range of 255 and moved to 128. I.e if the value you get from a or b channel is 128 that is actually 0, 120 would then be -8 and 135 would be +7. Thus you can just do a - 128 to get the negative value back.

What kind of ANN are you using? Backprop?

from United States  [214 posts] 12 years
Thanks STeven--that's exactly what I needed.  As for the ANN stuff, for the moment I am just using a Perceptron with the Delta Rule but I have Backprop waiting in the wings in case I need a multi-layered network.  I've been using the open source AForge.NET package from http://www.aforgenet.com/ which is really nicely written and easy to use (as you may already know!).


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