Though you’ll have to use it “cleverly.”) (Note that there’s also an Image Processing Toolbox function that facilitates the same calculation, Swag to the first person who can find, from among my File Exchange submissions, a function that generates the image above For example, using a function that I have previously shared on the File Exchange, I generated this color image:Ĭreating this image, using my function on my computer, took 0.02 seconds.
It also occurs to me that there are other approaches to the same problem. I’ll send a MATLAB cap to the first person who can exactly duplicate the results of colorIm generated above by vectorizing Jeny’s implementation of gray2rgb! Of this code, and I’m betting that some of our readers can as well. I can think of several ways to improve the performance The output image is generated by processing the converted images pixel by pixel (!), using a nested for loop. (The grayscale image is first expanded to 3D, with replicated information in the red, green, and blue colorplanes.) Then, A Multi-Part Challengeĭigging into the underlying code, we see that Jeny’s function converts both input images to 圜bCr. Of quality), or one could use “jittered sampling.” Unfortunately, no examples are provided that show how one would implement One could subsample the color image (at the potential cost Nonetheless, I’d like to note that this calculation took a very long time –on the order of two-and-a-half minutes ! Jeny discussed a couple of approaches to making this faster. There are several “thank you’s” and good reviews.
It’s clear that many people have found gray2rgb to be useful the file has been on the File Exchange for many years, and is getting close to 100 downloads per month. Here is a sample that shows what this function can do: figureĬolorIm = gray2rgb('liftingbody.png','gantrycrane.png') That is, you can provide a grayscale image along with a color image whose pallete you want to copy, and gray2rgb will create a color version of your grayscale image, matching (to some extent) the color of the second input image.
Recently, while browsing the File Exchange, I came across Jeny’s file, which allows one to convert images “the other way.” Converting to grayscale generally simplifies–and often speeds up–the processing of these color images.Ĭreating a grayscale image as a linear combination of multiple colorplanes is a common task, and one that the Image Processing Toolbox facilitates with the function rgb2gray. Is, I can usually get all of the information I need from one or more individual color planes, or from a grayscale representation Typically, when I’m analyzing color images, I find that I can do my analyses in “gray space” rather than in color space. (Who says the MATLAB Central Contest Team gets to have all the fun? :) ) If you’re interested, read on… Grayscale to RGB Jeny, of course, isĭue some swag–it’s on the way, Jeny! But I’ll also send MATLAB hats to four readers who can rise to the challenges I posedīelow. This week’s blog is image processing-centric, but it includes a challenge for MATLAB geeks everywhere. Win One of Several MATLAB Hats! Read On!! Happy Thanksgiving, and Happy MATLABbing!īrett‘s Pick this week is gray2rgb, by Jeny Rajan.Win One of Several MATLAB Hats! Read On!!.
0 kommentar(er)
