Why is the background of my custom marker changing color?

Hello,

I wanted to use images as custom markers for my plot. I have attached one of the images that I use as my marker. It is a binary image. however when I use it as a marker, the background of only the image becomes yellow. Is there any way to fix this?

x = 5:5:125;
y = 0:0.04:1; %some variation of the data

% Load the marker image:
markersize = [10,0.1]; 
x_low = x - markersize(1)/2;
x_high = x + markersize(1)/2;
y_low = y - markersize(2)/2;
y_high = y + markersize(2)/2;


for k = 1:length(x)
    marker = imread(['some_path\verify_threshold_images\', num2str(k),'cropped.tif']);
    plot(x,y)
    hold on
    imagesc([x_low(k) x_high(k)], [y_low(k) y_high(k)], marker);
end
axis ([0 140 0 1]);
hold off

[darova]

Are you sure your monitor is clear? Maybe it's just dirty?

[Meghana Balasubramanian]

Darova, please check the plot image I've attached. I'm sure your monitor screen isn't dirty.

[darova]

What about images you use for marker?

[Meghana Balasubramanian]

The image that I'm using for my marker is also attached as "8.jpg". I use the original tiff file but for viewing purposes on mathworks, I uploded the jpg format image. I don't thing the format of the image is affecting the code.

[Meghana Balasubramanian]

;_; Please help me. I'm losing my head over this

[Adam]

It depends entirely what is in 'cropped.tif'.

What do you get if you just do

marker = imread(['some_path\verify_threshold_images\',num2str(k),'cropped.tif']);
figure; imagesc( marker )

?

I don't know anything about .tiff format. Does it come with a colourmap you need to apply or is it true RGB?

[Meghana Balasubramanian]

The image being read in the code:

marker = imread(['some_path\verify_threshold_images\',num2str(k),'cropped.tif']);

is the same as the image attached, labeled as '8.jpg'.

My guess is that when I'm plotting the markers over the plot, to ensure that the markers are visible, imagesc manipulates the markers.

And as for the .tiff format, I don't apply any colormap.

[KALYAN ACHARJYA]

Sorry, I didnot get the question? Can you make it more simple (if possible)?

[Adam]

8.jpg is the jpg version of the image though, not the one you would plot from Matlab (on its own, without all the other stuff on the plot). Plus its a jpg, not a tiff

Answer 1

[Walter Roberson]

imagesc is primarily for pseudocolor images, especially ones in which the data is a range of values that is to be distributed over the current color map. You are not calling colormap() so you are getting whatever colormap happens to be in effect.

You should convert the cropped image into rgb and image() that. im2uint8() then repmat() 1,1,3 to create the rgb image.

[Meghana Balasubramanian]

Thank you for explaining it! This is just what I needed