How do I create a halftoning effect in MATLAB?
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How to make an image with halftoning effect that uses 75 lpi?
2 commentaires
Chaowei Chen
le 27 Août 2011
http://www.mathworks.com/matlabcentral/fileexchange/25303-image-halftoning-by-jarvis-method
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Saneem Ahmed
le 28 Août 2011
9 commentaires
Walter Roberson
le 31 Août 2011
fx and fy would be 400 for a screen or printer frequency of 400 dpi.
I did not attempt to locate a formula relating dpi and lpi with halftoning: it would depend upon what dot shape you were using and upon the cross-angle you were using. What I did is look at the table in that Wikipedia link and then did a linear interpolation between the 300 dpi and 600 dpi figures to estimate the minimum dpi that could handle 85 lpi (since the 600 dpi had 85 lpi as a lower bound, going up over 100 lpi, implying that you would be able to do 85 lpi with a lower dpi.)
DGM
le 27 Oct 2022
I'm going to completely ignore the issue of LPI and DPI. Something tells me that 20 people per month don't actually intend to feed this to a printer.
imgscale = 2; % scales the image
htmscale = 7; % scales the map WRT the image
% get an image and prepare it
inpict = imread('peppers.png');
inpict = im2double(rgb2gray(inpict));
inpict = imresize(inpict,imgscale);
% create constant-frequency map
s = size(inpict);
sc = imgscale*htmscale;
[xx yy] = meshgrid(1:s(2),1:s(1));
htm = 0.5*((cos(xx*2*pi./sc).*cos(yy*2*pi./sc))+1);
% perform thresholding
mask = inpict>htm;
% display it
imshow(mask)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1170708/image.png)
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