{"id":5636,"date":"2022-07-14T11:17:30","date_gmt":"2022-07-14T15:17:30","guid":{"rendered":"https:\/\/blogs.mathworks.com\/steve\/?p=5636"},"modified":"2022-07-14T11:17:30","modified_gmt":"2022-07-14T15:17:30","slug":"using-imsplit","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/steve\/2022\/07\/14\/using-imsplit\/","title":{"rendered":"How to use IMSPLIT to split a color image into component images"},"content":{"rendered":"
Today I want to show you a handy little function, <\/span>imsplit<\/span>, for splitting color images into their components.<\/span><\/div>
Also, for no reason other than <\/span>WOW<\/span>, I want to show one of the images just released by the James Webb Space Telescope program (<\/span>home page<\/span><\/a>, <\/span>flickr galleries<\/span><\/a>).<\/span><\/div>
url = <\/span>\"https:\/\/live.staticflickr.com\/65535\/52211883534_7fe30b9955_o_d.png\"<\/span>;<\/span><\/span><\/div><\/div>
rgb = imread(url);<\/span><\/span><\/div><\/div>
imshow(rgb)<\/span><\/span><\/div><\/div>
text(size(rgb,2),size(rgb,1),<\/span>\"Image credits: NASA, ESA, CSA, and STScl\"<\/span>,<\/span>...<\/span><\/span><\/div><\/div>
VerticalAlignment = <\/span>\"top\"<\/span>,<\/span>...<\/span><\/span><\/div><\/div>
HorizontalAlignment = <\/span>\"right\"<\/span>)<\/span><\/span><\/div>
<\/div>
<\/div>
<\/div>
<\/div><\/div><\/div><\/div><\/div>
Anyway, back to <\/span>imsplit<\/span>. Long-time readers have seen me use code like this to split up color images (sometimes RGB, sometimes <\/span>$ L^* a^* b^* $<\/span>) into component images:<\/span><\/div>
L = lab(:,:,1);<\/span><\/span><\/div>
a = lab(:,:,2);<\/span><\/span><\/div>
b = lab(:,:,3);<\/span><\/span><\/div><\/div>
See, for example, the posts about two-dimensional histograms (<\/span>23-Dec-2010<\/span><\/a>) and segmenting images in <\/span>$ (a^*,b^*) $<\/span> space (<\/span>04-Feb-2011<\/span><\/a>).<\/span><\/div>
That code is not hard to write, but now I've become fond of using <\/span>imsplit<\/span> instead, just because it is a bit more compact, without sacrificing understandability. The function <\/span>imsplit<\/span>, introduced in release R2018b, is used this way:<\/span><\/div>
url = <\/span>\"https:\/\/blogs.mathworks.com\/images\/steve\/2010\/mms.jpg\"<\/span>;<\/span><\/span><\/div><\/div>
candy = imread(url);<\/span><\/span><\/div><\/div>
lab = rgb2lab(candy);<\/span><\/span><\/div><\/div>
[L,a,b] = imsplit(lab);<\/span><\/span><\/div><\/div>
tiledlayout(<\/span>\"flow\"<\/span>)<\/span><\/span><\/div>
<\/div>
<\/div>
<\/div>
<\/div><\/div><\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(candy)<\/span><\/span><\/div><\/div>
 <\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(L,[0 100])<\/span><\/span><\/div><\/div>
title(<\/span>\"L\"<\/span>)<\/span><\/span><\/div><\/div>
 <\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(a,[-90 90])<\/span><\/span><\/div><\/div>
title(<\/span>\"a\"<\/span>)<\/span><\/span><\/div><\/div>
 <\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(b,[-90 90])<\/span><\/span><\/div><\/div>
title(<\/span>\"b\"<\/span>)<\/span><\/span><\/div><\/div><\/div>
That's it, really. There's nothing more to it. Give it a try the next time you need to do this; it'll save you 2.7183 seconds.<\/span><\/div>
Before I go, let's look at that Webb telescope image one more time, just because.<\/span><\/div>
[R,G,B] = imsplit(rgb);<\/span><\/span><\/div><\/div>
tiledlayout(<\/span>\"flow\"<\/span>)<\/span><\/span><\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(rgb)<\/span><\/span><\/div><\/div>
 <\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(R)<\/span><\/span><\/div><\/div>
title(<\/span>\"R\"<\/span>)<\/span><\/span><\/div><\/div>
 <\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(G)<\/span><\/span><\/div><\/div>
title(<\/span>\"G\"<\/span>)<\/span><\/span><\/div><\/div>
 <\/div><\/div>
nexttile<\/span><\/span><\/div><\/div>
imshow(B)<\/span><\/span><\/div><\/div>
title(<\/span>\"B\"<\/span>)<\/span><\/span><\/div>
<\/div>
<\/div>
<\/div>
<\/div><\/div><\/div><\/div><\/div>
<\/div>\r\n<\/div>