Java - Unable to read JPEG image using ImageIO.read(File file) CV Dazzle: Camouflage From Computer Vision by Adam Harvey. How to reduce the file size of a PNG file. PNG files are lossless compressed bitmapped images. While they are compressed, they can still attain large file sizes depending on the type of image data saved—they are best suited for images with large areas of solid colours and defined boundaries (such as logos). Unlike JPG files, they are not especially suited for storing photographic image data. Optimized PNG files are smaller than GIF files, and support higher-quality transparency. Compression Tools Edit Lossy Edit Biggest savings can be achieved at a cost of reducing image quality a little: TinyPNG online tool that uses lossy compression to reduce the file size of PNG images ImageAlpha Mac tool that can reduce PNG files using pngquant, pngnq and posterization.
Lossless These tools don't lose any quality, they only re-compress images and remove invisible metadata: There are also online tools available that can compress PNG files. Is a service provided by Yahoo! See Also. Histogrammes, et Ajustement Gaussien. Syntactic Bay Leaves - Determining image similarity. When I saw this question on stackoverflow asking about how to determine if an image is identical, it reminded me of my favorite class at JHU, Computer Vision.
One of the things that I remember is that if you wanted to compute how similar two images are, you’d treat their pixels as vectors, normalize them, then take their dot product. The result is a float between 0 and 1 that indicated the percent similarity of the two images. This process is called the normalized cross correlation. After you got that number, it was a matter of setting a threshold as to what you wanted to accept as similar or not. For fun, I whipped up a naive implementation of normalized cross correlation in Python using PIL and numpy: It’s pretty slow, taking about a minute to process two 400k jpegs on my MacBook Pro, but I bet there’s a nice way to parallelize it (maybe using Python 2.6′s sweet new multiprocessing module?). Www-rech.telecom-lille1.eu/coresa2004/articles/p064-lachkar.pdf.