imrect
in [Matlab]
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From: Kris zenitis on 19 May 2010 20:45 Hallo there!! I have this code which mark specific rectangles in a graysclae picture function M = imrect(I,ltx,lty,rbx,rby) % IMRECT Draw Rectangles on an Gray-level Image % imrect(I), where I is an Gray-level image matrix % ltx(i), lty(i): left top (x,y) % rbx(i), rby(i): right bottom (x,y) % return M, the image matrix with rectangles drawed. len = length(ltx); for i=1:len for p=ltx(i):rbx(i) I(lty(i),p) = 0; I(rby(i),p) = 0; end for p=lty(i):rby(i) I(p,ltx(i)) = 0; I(p,rbx(i)) = 0; end end M = I; Firstly I want to use imrect in colourful picture and to have colour rectangular(or secondly just to have colourful rectangles in a grayscale picture). How can I cope with the first question? And it is possible the second?
From: Walter Roberson on 19 May 2010 21:09 Kris zenitis wrote: > Firstly I want to use imrect in colourful picture and to have colour > rectangular Have you tried just rect() and set the EdgeColor and FaceColor for that rectangle ? > (or secondly just to have colourful rectangles in a grayscale > picture). If you use rect() it will not form part of the image itself; rect() does not care what kind of image might happen to be below it.
From: ImageAnalyst on 19 May 2010 22:14 imrect() is a reserved function name in the Image Processing Toolbox. If you have, or ever plan on using that toolbox, you should avoid using the function name imrect for your own custom functions or you will override the built-in imrect(). It's also not a great idea to use I as a variable name. I know it's case sensitive (so won't get confused with i, the imaginary number) but it seems like you're on the slippery slope of using bad variable and function names so it might be good to start improving on that. Otherwise you'll soon start doing things like using i for index variable names - oh wait, you already did that too. Bummer. Here's a little demo on using imellipse to create outline and solid masks and to burn them into the image (like you want to do). Adapting it for imrect is simple and straightforward. By the way, you might want to note how instructive it is that I use descriptive variable names - imagine what a confusing mess it would be if all my variables were 1 or 2 letters. clc; clear; close all; workspace; % Change the current folder to the folder of this m-file. % (The line of code below is from Brett Shoelson of The Mathworks.) if(~isdeployed) cd(fileparts(which(mfilename))); end filename = 'C:\Program Files\MATLAB\R2010a\toolbox\images\imdemos \cell.tif'; % Standard demo image. originalImage = imread(filename); subplot(3, 2,1); imshow(originalImage, []); title('Original Image'); set(gcf, 'Position', get(0, 'ScreenSize')); % Maximize figure. [rows, columns, numberOfColors] = size(originalImage) % Make a solid ellipse. rowVector = linspace(1, rows, rows); colVector = linspace(1, columns, columns); [x,y] = meshgrid(colVector, rowVector); size = .5; semiAxisX = columns / 2; semiAxisY = rows / 4; centerX = columns / 2; centerY = rows / 2; solidEllipse = ( ((x-centerX)/semiAxisX).^2 + ((y-centerY)/ semiAxisY).^2 <= size); subplot(3, 2, 3); imshow(solidEllipse); title('Solid Ellipse'); % Make just a perimeter of an ellipse. smallerEllipse = imerode(solidEllipse, ones(3)); perimeterEllipse = logical(solidEllipse - logical(smallerEllipse)); subplot(3, 2, 4); imshow(perimeterEllipse); title('Perimeter Ellipse'); % Write the solid ellipse into the image and display it. originalPlusSEllipse = originalImage; originalPlusSEllipse(solidEllipse) = 255; subplot(3, 2, 5); imshow(originalPlusSEllipse); title('Solid Ellipse Written into Original Image'); % Write the perimeter ellipse into the image and display it. originalPlusPEllipse = originalImage; originalPlusPEllipse(perimeterEllipse) = 255; subplot(3, 2, 6); imshow(originalPlusPEllipse); title('Perimeter Ellipse Written into Original Image');
From: Kris zenitis on 20 May 2010 19:21 ok thanks a lot for your help. The above fantastic code is to draw elipse i want rectangulars. I ve been confused a little. I must change the elipse to rectangular and after that how i manage with the coordinates?
From: ImageAnalyst on 20 May 2010 21:52
On May 20, 7:21 pm, "Kris zenitis" <gio.1...(a)hotmai.com> wrote: > ok thanks a lot for your help. The above fantastic code is to draw elipse i want rectangulars. I ve been confused a little. I must change the elipse to rectangular and after that how i manage with the coordinates? ---------------------------------------------------------------- I'm not even sure what your intent is. Do you want to change your image by "burning" new values into it? To do that, you'd assign pixel values like you're doing, but in a vectorized way instead of in loops. If you want to burn colored lines into the image then you'd have to convert your grayscale image into a color image with the cat(3, grayImage, grayImage, grayImage) command, or the ind2rgb(grayImage) command. Or do you just want to display a rectangle over your image, say with the plot() function? This will not change your image pixel values at all, it will just put a rectangle over your image, in whatever color you specify. plot([x1 x2 x2 x1 x1], [y1 y1 y2 y2 y1], 'Color', [1 1 0]); |