SummaryThis document covers selected image processing applications. Optical character recognition is the translation of images of handwritten, typed, or printed text into machine-editable text. Then I introduced the captcha that we encounter so often on common websites. An algorithm that attempts to solve or crack a captcha has been explained. Face detection is an important and growing tool in security today. Must be applied before facial recognition. There are many methods to recognize faces and some of them are discussed in the paper. ContentsTopic Pg NoImage ProcessingOptical Character RecognitionCaptchaBrakingCaptchaFace DetectionFace Detection AlgorithmReferencesImage ProcessingImage processing is any form of signal processing for which the input is an image, such as photographs or video frames; the output of image processing can be an image or a set of features or parameters related to the image. Most image processing techniques involve treating the image as a two-dimensional signal and applying standard signal processing techniques to it. Typical operations Among many other image processing operations are: Geometric transformations such as enlargement, reduction and rotation Color corrections such as brightness and contrast adjustments, quantization or conversion to a different color space Digital composition or optical composition (combination of two or more images). Interpolation, demosaicing and recovery of a complete image from a raw image format. Image editing (for example, to increase the quality of a digital image) Image differentiation (to determine the changes between images) Image registration (aligning two or more images) Image stabilization Image segmentation (dividing a digital image into multiple regions) Dynamic range extension by combining differently exposed images object recognition 2-D with affine invarianceOptical character recognitionOptical character recognition, usually abbreviated to OCR, is the mechanical or electronic translation of images of handwritten, typed, or printed text (usually captured by a scanner) into editable text.OCR is a field of research in pattern recognition, artificial intelligence, and computer vision. While academic research in the field continues, the focus in OCR has shifted to implementing proven techniques. Optical character recognition (using optical techniques such as mirrors and lenses) and digital character recognition (using scanners and computer algorithms) were originally considered separate fields. Since very few applications using true optical techniques survive, the term OCR has now been expanded to also include digital image processing. Early systems required training (the provision of known samples of each character) to read a specific character. "Intelligent" systems with a high degree of recognition accuracy for most characters are now common.