I am having problems to generate a sine-wave Gabor grating. Can someone help please?

Hello! I am trying to use a code provided from a book to generate a gabor sine-ave grating stimulus. In this book they suggest we create a function first, called showImage:

%%% Program showImage.m function gca = showImage(M, lut_type) gca = fi gure; % Opens a graphics window image(M); % Display image M in the graphics window axis( ‘ image ’ ); % Sets axis properties of the image in the % graphics window axis( ‘ off ’ ); % Turn off the axes if strcmp(lut_type, ‘ grayscale ’ ) % Check if lut_type is % grayscale lut = [(0:255) ′ (0:255) ′ (0:255) ′ ]/255; colormap(lut); else colormap( ‘ default ’ ); % Use Matlab ’ s default colormap end

The problem is at the fifth last line: lut = [(0:255) ′ (0:255) ′ (0:255) ′ ]/255; the (') symbols seems odd! They appear in 3, not in a even number. Can someone correct this code? Thank you!

Answer 1

[Bob Blaine]

Hi Caroline,

I'm not sure of the exact problem that you are having, but if you do the following:

surf(peaks)
lut = [(0:255)' (0:255)' (0:255)' ]/255;
colormap(lut);

You get a nice grayscale display of peaks. The ' mark transposes the number list in the parens so you end up with a matrix with 256 rows and 3 columns. I suspect that there's a syntax problem in your code that I can't see.

Answer 2

[Caroline Alencar]

I replaced my "lut" line for yours and it worked! Thank you!