Scala Kuva is a Scala library that focuses on image and color processing and filtering.
The library contains implementations for three color formats: RGB(A), HSL(A), and HSV(A). These color types are immutable and can be converted between each other. Additionally, they can also be converted to java.awt.Color and created from it
For all image operations in this library own implementation of the immutable image is used. The Immutable image simply wraps two-dimensional Vector of immutable Pixels, offering some useful operations to work with it in functional way.
It can also be converted to java.awt.image.BufferedImage and created from it.
This library contains implementation for various color and image operations. For example: most grayscale algorithms, many blend modes, binarization, resizing with different algorithms, croping and more.
This initial image will be used to demonstrate the effects of the different operations.
Example image is downscaled (from 1024x1280 to 400 x 500) using nearest neighbor algorithm.
Example image is upscaled (from 128x160 to 1024x1280) using nearest neighbor algorithm.
Example image is upscaled (from 128x160 to 1024x1280) using bilinear interpolation.
Example image is upscaled (from 128x160 to 1024x1280) using bicubic interpolation.
The average hash algorithm works by converting an image into a grayscale, downsampling it to a small size (8x8 per default), computing the average pixel value, and creating a binary hash by comparing each pixels value with the average value.
The average hash algorithm works by converting an image into a grayscale, downsampling it to a small size (8x8 per default), computing the median pixel value, and creating a binary hash by comparing each pixels value with the median value.
The difference hash algorithm works by converting an image into a grayscale, downsampling it to a small size (9x8 per default), and by computing the difference in pixel values between adjacent pixels (compares each pixel with the pixel on the right from it).
This algorithm simply uses average of all color channels as grayscale color.
Calculates max value of 3 color channels and uses it as grayscale color.
Calculates min value of 3 color channels and uses it as grayscale color.
This algorithm first convert color to HSL and then reduces saturation to 0.
Calculate grayscale color using luma (luminance or brightness) formula (from ITU-R BT 601 specification).
Also calculates grayscale color using luma formula, but from newer standard (ITU-R BT 709). The weighting coefficients used in the formulas are different between the two standards.
Uses as grayscale color the value of red color channel
Uses as grayscale color the value of green color channel
Uses as grayscale color the value of blue color channel
Calculates and uses as grayscale lightness using formula from this paper.
Calculates and uses as grayscale lightness using formula from HSL color format.
Calculates and uses as grayscale middle value of the RGB channels
Converts grayscale image to grayscale image with limited number of shades. (Example image has 8 shades of gray)
Color inversion is a photo effect that flips all colors to their opposite hue on the color wheel (with inversion of alpha channel or without).
To demonstrate different color blending algorithms two abstract (background and foreground) images will be used. (There also additional examples in src/main/resources/source/blend/gradient folder)
Background (initial image):
Foreground (overlay image):
Binarization is the process of converting a multi-tone grayscale image into a two-tone black and white image. This is achieved by finding a threshold value, which is then used to create the binary output.
Otsu's method is a thresholding technique used to separate an image into foreground and background pixels. It calculates the optimal threshold value by maximizing the between-class variance of pixel intensities.
Otsu's method requires the image to be converted into grayscale before applying the algorithm, and the resulting threshold value may vary depending on the specific grayscale conversion algorithm used.
