Learning Matlab at uni, need some help

a. Create horizontal lines across the image by making every 8th row of the image a row of white pixels (value = 254). View result.

b. Do the same in the vertical direction to create a grid over the image. View result.

c. Extract only the woman’s face and view this section only (Turn the axis on to help you identify which parts of the matrix to index. Use: axis on to do this).

My Code:

load woman;
for i=1:8:length(X)
    X(i,:)=254;
    X(:,i)=254;
end

axis on
imshow(uint8(X));

Have i done this correct, with the axis on?

Answer 1

[Adam]

X(1:8:end,:) = 254;
X(:,1:8:end) = 254;

would do the job rather than using a for loop.

[Andrew]

thanks man, really simplifies it.

Answer 2

[Image Analyst]

Since it says "over" the image rather than "in" the image, I'd put lines into the overlay using "hold on" and then the line() function. Try that.

Then to "extract" I can't tell because you didn't include the image. Perhaps you can threshold or do color segmentation, or perhaps you can simply crop with imcrop() at specified coordinates. "Extract" is ambiguous so it could mean either of those. It's probably the latter since it hinted to turn on the axis tick marks.

[Andrew]

yeah, sounds good. ill work on it