I’m Martin’s friend who was working on this earlier this year. This was my first ever coding project, and kinda ended in a bit of a rush, so the code needs some errr…decoding… I’ll give a few tips from what I’ve seen you doing already, and then sort my code on my day off tomorrow. … Read more
The specific numbers in the question are from CCIR 601 (see Wikipedia article). If you convert RGB -> grayscale with slightly different numbers / different methods, you won’t see much difference at all on a normal computer screen under normal lighting conditions — try it. Here are some more links on color in general: Wikipedia … Read more
One general procedure is laid out in the Wikipedia article on unsharp masking: You use a Gaussian smoothing filter and subtract the smoothed version from the original image (in a weighted way so the values of a constant area remain constant). To get a sharpened version of frame into image: (both cv::Mat) cv::GaussianBlur(frame, image, cv::Size(0, … Read more
Here is a list of commercial vendors that provide off-the-shelf packages for facial recognition which run on Windows: Cybula – Information on their Facial Recognition SDK. This is a company founded by a University Professor and as such their website looks unprofessional. There’s no pricing information or demo that you can download. You’ll need to … Read more
fix DPI (if needed) 300 DPI is minimum fix text size (e.g. 12 pt should be ok) try to fix text lines (deskew and dewarp text) try to fix illumination of image (e.g. no dark part of image) binarize and de-noise image There is no universal command line that would fit to all cases (sometimes … Read more
Can the screenshot or icon be transformed (scaled, rotated, skewed …)? There are quite a few methods on top of my head that could possibly help you: Simple euclidean distance as mentioned by @carlosdc (doesn’t work with transformed images and you need a threshold). (Normalized) Cross Correlation – a simple metrics which you can use … Read more
Another very simple way to estimate the sharpness of an image is to use a Laplace (or LoG) filter and simply pick the maximum value. Using a robust measure like a 99.9% quantile is probably better if you expect noise (i.e. picking the Nth-highest contrast instead of the highest contrast.) If you expect varying image … Read more
I use always: quality in 85 progressive (comprobed compression) a very tiny gausssian blur to optimize the size (0.05 or 0.5 of radius) depends on the quality and size of the picture, this notably optimizes the size of the jpeg. Strip any comment or EXIF metadata in imagemagick should be convert -strip -interlace Plane -gaussian-blur … Read more
I’ve found Waldo! How I’ve done it First, I’m filtering out all colours that aren’t red waldo = Import[“http://www.findwaldo.com/fankit/graphics/IntlManOfLiterature/Scenes/DepartmentStore.jpg”]; red = Fold[ImageSubtract, #[[1]], Rest[#]] &@ColorSeparate[waldo]; Next, I’m calculating the correlation of this image with a simple black and white pattern to find the red and white transitions in the shirt. corr = ImageCorrelate[red, Image@Join[ConstantArray[1, {2, … Read more