heatmap color RGB data for manaully created image

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I have the usage data for they key use on a qwerty keyboard. I would like to create a heat map on the image of a traditional keyboard (made at the end).
I really like how heatmap works with the color scheme. How can I get the color information from the heatmap for my keyboard? How can I can I find the RGB values for each key?
I found similiar questions to this, but they were not clear.
% Given data: the sum of Data is equal to 1
% sum(data) = 1 is True
data = [0.000185322461082283 0.0209811500582442 0.121240601503759 0.0536905644392672 0.0794967171449751 0.0211333792227047 0.0234035793709626 0.0543855236683257 0.0746584771788626 0.0124761728264323;...
0.0893254262416605 0.0582243460764588 0.0493354866038335 0.0234763846235307 0.0161164354548343 0.0785303928836175 0.0033556602774542 0.00686354971936884 0.0357407603515832 0.0146801863814466;...
0.000781001800275336 0.000344170284867097 0.0167716827279466 0.00929921635073599 0.0168974372551096 0.0614145398708038 0.0265209679127396 0.0195912316001271 0.0101066927883088 0.000972942920681987];
layout =[ "q" "w" "e" "r" "t" "y" "u" "i" "o" "p"
"a" "s" "d" "f" "g" "h" "j" "k" "l" ";"
"z" "x" "c" "v" "b" "n" "m" "," "." "/"];
% heatmap generate
figure(1)
fig = heatmap(data,'Colormap',parula)
fig =
HeatmapChart with properties: XData: {10×1 cell} YData: {3×1 cell} ColorData: [3×10 double] Show all properties
% values found for the making image, key size, key widths
key_num_width = 10.80;
key_num_hieght = 3;
key_pixel = 30;
size_multiplier = 10; % mess with this to change resolution probably something close to 10
% I forget what this does
A = 255*ones(size_multiplier*key_num_hieght*key_pixel,size_multiplier*key_num_width*key_pixel);
[B, C] = deal(A);
key_size = size_multiplier*key_pixel;
% changes the ones to 255 for image
rgbImage(:,:,1) = uint8(A);
rgbImage(:,:,2) = uint8(B);
rgbImage(:,:,3) = uint8(C);
Here, I need the data which are the three RGB matrixes each being 3x10
% HERE
% I would like to find the RGB matrix values from the heatmap
R_value = 200*ones(3,10)
R_value = 3×10
200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
G_value = 200*ones(3,10)
G_value = 3×10
200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
B_value = 200*ones(3,10)
B_value = 3×10
200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200
% specify key colors given R, G and B matrixes (all 3x10) that has been
% extracted from heatmap
% starts top row (left to right) and then down each row one at a time
offset = [0 0.25 0.75]; % offset for key rows
for j = 0:2
% specifies the boundries in the y directions for the keys
ywidth = (key_size*j+1):(key_size+key_size*j);
for i = 0:9
% specifies the boundries in the x directions for the keys
% note that there is a offset applied at 0, 0.25 and 0.75 of
% keywidth
xwidth = (key_size*i+1+key_size*offset(j+1)):(key_size+key_size*i+key_size*offset(j+1));
% apply found RGB values from heat map to key at a time
rgbImage(ywidth,xwidth,1) = R_value(j+1,i+1);
rgbImage(ywidth,xwidth,2) = G_value(j+1,i+1);
rgbImage(ywidth,xwidth,3) = B_value(j+1,i+1);
end
end
% enter text for each key, included in question for clarity
RGB = rgbImage;
for i = 0:9
RGB = insertText(RGB,[ key_size/2+i*key_size,key_size/2],layout(1,i+1),'FontSize',150,'AnchorPoint','Center','BoxOpacity',0);
end
for i = 0:9
RGB = insertText(RGB,[key_size/2+i*key_size+key_size*0.25,key_size/2+key_size],layout(2,i+1),'FontSize',150,'AnchorPoint','Center','BoxOpacity',0);
end
for i = 0:9
RGB = insertText(RGB,[key_size/2+i*key_size+0.75*key_size,key_size/2+key_size*2],layout(3,i+1),'FontSize',150,'AnchorPoint','Center','BoxOpacity',0);
end
% show result
figure(2)
imshow(RGB)
  3 Comments
Adam Danz
Adam Danz on 4 Aug 2022
This is the first time I see a heat map created with insertText! Ha! Creative.

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Accepted Answer

DGM
DGM on 4 Aug 2022
Edited: DGM on 4 Aug 2022
The use of heatmap() is unnecessary. This is a basic use of indexed color. Generate a color table and find the indexes into it.
data = [0.000185322461082283 0.0209811500582442 0.121240601503759 0.0536905644392672 0.0794967171449751 0.0211333792227047 0.0234035793709626 0.0543855236683257 0.0746584771788626 0.0124761728264323;...
0.0893254262416605 0.0582243460764588 0.0493354866038335 0.0234763846235307 0.0161164354548343 0.0785303928836175 0.0033556602774542 0.00686354971936884 0.0357407603515832 0.0146801863814466;...
0.000781001800275336 0.000344170284867097 0.0167716827279466 0.00929921635073599 0.0168974372551096 0.0614145398708038 0.0265209679127396 0.0195912316001271 0.0101066927883088 0.000972942920681987];
ctlength = 256; % pick a color table length
CT = parula(ctlength); % generate a color table
ctidx = round(mat2gray(data)*(ctlength-1)) % these are the corresponding row indices into CT
ctidx = 3×10
0 44 255 113 167 44 49 114 157 26 188 122 104 49 34 165 7 14 75 31 1 0 35 19 35 129 55 41 21 2
What is the color associated with data(1,3)?
CT(ctidx(1,3)+1,:)
ans = 1×3
0.9769 0.9839 0.0805
All you need to do at this point is apply that color to the image regions.
  6 Comments
Adam Danz
Adam Danz on 4 Aug 2022
Edited: Adam Danz on 4 Aug 2022
@DGM, normalize(A,'range') is similar and doesn't require Image Processing TB but it currently doesn't have an option to specify both the "range" method and the dimensions.
B = rescale(A) is even better IMO.

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More Answers (1)

Adam Danz
Adam Danz on 4 Aug 2022
See the 5 lines of code under "new section". I didn't change anything else.
% Given data: the sum of Data is equal to 1
% sum(data) = 1 is True
data = [0.000185322461082283 0.0209811500582442 0.121240601503759 0.0536905644392672 0.0794967171449751 0.0211333792227047 0.0234035793709626 0.0543855236683257 0.0746584771788626 0.0124761728264323;...
0.0893254262416605 0.0582243460764588 0.0493354866038335 0.0234763846235307 0.0161164354548343 0.0785303928836175 0.0033556602774542 0.00686354971936884 0.0357407603515832 0.0146801863814466;...
0.000781001800275336 0.000344170284867097 0.0167716827279466 0.00929921635073599 0.0168974372551096 0.0614145398708038 0.0265209679127396 0.0195912316001271 0.0101066927883088 0.000972942920681987];
layout =[ "q" "w" "e" "r" "t" "y" "u" "i" "o" "p"
"a" "s" "d" "f" "g" "h" "j" "k" "l" ";"
"z" "x" "c" "v" "b" "n" "m" "," "." "/"];
% heatmap generate
figure(1)
fig = heatmap(data,'Colormap',parula)
fig =
HeatmapChart with properties: XData: {10×1 cell} YData: {3×1 cell} ColorData: [3×10 double] Show all properties
% values found for the making image, key size, key widths
key_num_width = 10.80;
key_num_hieght = 3;
key_pixel = 30;
size_multiplier = 10; % mess with this to change resolution probably something close to 10
% I forget what this does
A = 255*ones(size_multiplier*key_num_hieght*key_pixel,size_multiplier*key_num_width*key_pixel);
[B, C] = deal(A);
key_size = size_multiplier*key_pixel;
% changes the ones to 255 for image
rgbImage(:,:,1) = uint8(A);
rgbImage(:,:,2) = uint8(B);
rgbImage(:,:,3) = uint8(C);
% HERE
% % I would like to find the RGB matrix values from the heatmap
% R_value = 200*ones(3,10)
% G_value = 200*ones(3,10)
% B_value = 200*ones(3,10)
New section
cmap = uint8(parula(256) * 255);
cidx = round(normalize(data(:),'range')*(height(cmap)-1))+1;
R_value = reshape(cmap(cidx,1),size(data));
G_value = reshape(cmap(cidx,2),size(data));
B_value = reshape(cmap(cidx,3),size(data));
% specify key colors given R, G and B matrixes (all 3x10) that has been
% extracted from heatmap
% starts top row (left to right) and then down each row one at a time
offset = [0 0.25 0.75]; % offset for key rows
for j = 0:2
% specifies the boundries in the y directions for the keys
ywidth = (key_size*j+1):(key_size+key_size*j);
for i = 0:9
% specifies the boundries in the x directions for the keys
% note that there is a offset applied at 0, 0.25 and 0.75 of
% keywidth
xwidth = (key_size*i+1+key_size*offset(j+1)):(key_size+key_size*i+key_size*offset(j+1));
% apply found RGB values from heat map to key at a time
rgbImage(ywidth,xwidth,1) = R_value(j+1,i+1);
rgbImage(ywidth,xwidth,2) = G_value(j+1,i+1);
rgbImage(ywidth,xwidth,3) = B_value(j+1,i+1);
end
end
% enter text for each key, included in question for clarity
RGB = rgbImage;
for i = 0:9
RGB = insertText(RGB,[ key_size/2+i*key_size,key_size/2],layout(1,i+1),'FontSize',150,'AnchorPoint','Center','BoxOpacity',0);
end
for i = 0:9
RGB = insertText(RGB,[key_size/2+i*key_size+key_size*0.25,key_size/2+key_size],layout(2,i+1),'FontSize',150,'AnchorPoint','Center','BoxOpacity',0);
end
for i = 0:9
RGB = insertText(RGB,[key_size/2+i*key_size+0.75*key_size,key_size/2+key_size*2],layout(3,i+1),'FontSize',150,'AnchorPoint','Center','BoxOpacity',0);
end
% show result
figure(2)
imshow(RGB)
  1 Comment
Taybs
Taybs on 4 Aug 2022
Edited: Taybs on 4 Aug 2022
Thank you so much. I appreciate it. I saw the edits that you made as well.

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