imagefilter

Enhancing the image can be performed by adjusting the brightness, contrast, saturation etc. of that image. In the Phimpme Android Image Application, we implemented many enhancement operations. All these image enhancement operations are performed by the native image processing functions. An image is made up of color channels. A gray-scale image has a single channel, colored opaque image has three channels and colored image with transparency has four channels. Each color channel of an image represents a two dimensional matrix of integer values. An image of resolution 1920x1080 has 1920 elements in its row and 1080 such rows. The integer values present in the matrices will be ranging from 0 to 255. For a grayscale image there will be a single channel. So, for that image, 0 corresponds to black color and 255 corresponds to white color. By changing the value present in the matrices, the image can be modified. The implementation of the enhancement functions in Phimpme Application are given below. Brightness Brightness adjustment is the easiest of the image processing functions in Phimpme. Brightness can be adjusted by increasing or decreasing the values of all elements in all color channel matrices. Its implementation is given below. void tuneBrightness(Bitmap* bitmap, int val) {  register unsigned int i;  unsigned int length = (*bitmap).width * (*bitmap).height;  unsigned char* red = (*bitmap).red;  unsigned char* green = (*bitmap).green;  unsigned char* blue = (*bitmap).blue;  signed char bright = (signed char)(((float)(val-50)/100)*127);  for (i = length; i--; ) {       red[i] =  truncate(red[i]+bright);       green[i] = truncate(green[i]+bright);       blue[i] = truncate(blue[i]+bright);  } }    low brightness, normal, high brightness(in the order) images are shown above For the above function, the argument val is given by the seekbar implemented in java activity. Its value ranges from 0 - 100, so a new variable is introduced to change the range of the input argument in the function. You can see that in the for loop there is function named truncate. As the name suggests it truncates the input argument’s value to accepted range. It is added to the top of the c file as below #define truncate(x) ((x > 255) ? 255 : (x < 0) ? 0 : x) Contrast Contrast of an image is adjusted in Phimpme application by increasing the brightness of the brighter pixel and decreasing value of the darker pixel. This is achieved by using the following formula for the adjustment contrast in editor of phimpme application. pixel[i] = {(259 x (C + 255))/(255 x (259 - C))} x (pixel[i] - 128) In the above formula, C is the contrast value and pixel[i] is the value of the element in the image matrix that we are modifying for changing the contrast.   low contrast, normal, high contrast(in the order) images are shown above So, after this formula for modifying every pixel value, the function looks like below void tuneContrast(Bitmap* bitmap, int val) {  register unsigned int i;  unsigned int length = (*bitmap).width * (*bitmap).height;  unsigned char* red = (*bitmap).red;  unsigned char* green = (*bitmap).green;  unsigned char*…