I just managed to tell ImageMagick about the fonts on my OSX system like this: # Make a new directory for ImageMagick local settings and cd into it mkdir ~/.magick cd ~/.magick # Grab script to find all fonts on system and store them in a config file curl -L http://www.imagemagick.org/Usage/scripts/imagick_type_gen > type_gen # Run … 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
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
Dithering Well I got some time for this today so here the result. You did not provide your plotter color palette so I extracted it from your resulting images but you can use any. The idea behind dithering is simple our perception integrates color on area not individual pixels so you have to use some … Read more
A quick guide to Caffe’s convert_imageset Build First thing you must do is build caffe and caffe’s tools (convert_imageset is one of these tools). After installing caffe and makeing it make sure you ran make tools as well. Verify that a binary file convert_imageset is created in $CAFFE_ROOT/build/tools. Prepare your data Images: put all images … 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
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
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