How do I draw a colour bar with known discrete RGB values and known percentage of pixels represent each RGB values?

2 次查看（过去 30 天）
Salad Box
Salad Box 2018-1-24
编辑： Jan 2018-1-25
Hi,
I extracted 3 key colours from an image using clustering method. The RGB values of the 3 colours are as below:
RGB1=[24 70 187]; (blue)
RGB2=[208 118 22]; (orange)
RGB3=[88 90 28]; (olive green)
My question is:
How to draw a colour bar (shown below) in matlab with the 3 known colours and the known percentage of the pixels represent each colour (blue 50%, orange 30%, and olive green 20%). In this fashion it tells that the dominant colour extracted from the image is blue followed by orange, then olive green.
Currently this colour bar was drawn in photoshop unfortunately.

请先登录，再回答此问题。

采纳的回答

Jan
Jan 2018-1-24
编辑：Jan 2018-1-24
As pixel image:
Map = [24 70 187; 208 118 22; 88 90 28] / 255;
Ind = repmat(repelem([1, 2, 3], [50, 30, 20]), 40, 1);
RGB = ind2rgb(Ind, Map);
figure;
image(RGB)
Or as patch:
Map = [24 70 187; 208 118 22; 88 90 28] / 255;
a = 0.5; b = 0.8;
vert = [0 0; 0 1; a 1; a 0; b 1; b 0; 1, 1; 1, 0];
face = [1, 2, 3, 4; 4, 3, 5, 6; 6, 5, 7, 8];
figure;
patch('Vertices', vert, 'Faces', face, ...
'FaceVertexCData', Map, ...
'FaceColor', 'flat', 'EdgeColor', 'none')
  2 个评论
Salad Box
Salad Box 2018-1-24
Hi Jan,
Thanks for your answer. It did solve 99.9% of my problem. The only 0.01% unsolved is that with your code for pixel image I get:
Instead of getting the output image with a slightly high height (h), how can I get a low height (h1) so it will look more like what I initially request? That would be really helpful.
Jan
Jan 2018-1-24
编辑：Jan 2018-1-25
You can control the dimension of a displayed image by setting the 'Position' of the axes:
axes('Position', [0.1, 0.1, 0.8, 0.1], ...
'visible', 'off', 'NextPlot', 'add');
image(RGB);
Or by defining the Y-limits. The same works for the patch object.

请先登录，再进行评论。

更多回答（1 个）

Benjamin Kraus
Benjamin Kraus 2018-1-24
You can use a patch object for this.
values = [0.5 0.3 0.2];
colors = [24 70 187; 208 118 22; 88 90 28]/255;
n = numel(values);
x = [0 cumsum(values)].*[1;1];
y = ones(2,n+1).*[1;0];
vertices = [x(:) y(:)];
faces = [1 2 4 3]+((2:2:2*n)-2)';
p = patch(...
'Vertices',vertices,...
'Faces',faces,...
'FaceVertexCData', colors, ...
'FaceColor', 'flat');
xlim([-0.1 1.1]);
ylim([-0.1 1.1]);

类别

在 Help Center 和 File Exchange 中查找有关 Image Arithmetic 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by