fpi_img_new ()

struct fp_img *
fpi_img_new (size_t length);

Creates a new fp_img structure with length bytes of data allocated to hold the image.

fpi_img_new_for_imgdev ()

struct fp_img *
fpi_img_new_for_imgdev (struct fp_img_dev *imgdev);

Creates a new fp_img structure, like fpi_img_new(), but uses the driver's advertised height and width to calculate the size of the length of data to allocate.

fpi_img_realloc ()

struct fp_img *
fpi_img_realloc (struct fp_img *img,
                 size_t newsize);

Changes the size of the data part of the fp_img.

fpi_img_resize ()

struct fp_img *
fpi_img_resize (struct fp_img *img,
                unsigned int w_factor,
                unsigned int h_factor);

Resizes the fp_img image by scaling it by w_factor times horizontally and h_factor times vertically.

fpi_std_sq_dev ()

int
fpi_std_sq_dev (const unsigned char *buf,
                int size);

Calculates the squared standard deviation of the individual pixels in the buffer, as per the following formula:

1
2

mean = sum (buf[0..size]) / size
sq_dev = sum ((buf[0.size] - mean) ^ 2)

This function is usually used to determine whether image is empty.

fpi_mean_sq_diff_norm ()

int
fpi_mean_sq_diff_norm (unsigned char *buf1,
                       unsigned char *buf2,
                       int size);

This function calculates the normalized mean square difference of two buffers, usually two lines, as per the following formula:

1

sq_diff = sum ((buf1[0..size] - buf2[0..size]) ^ 2) / size

This functions is usually used to get numerical difference between two images.

enum FpiImgFlags

Flags used in the fp_img structure to describe the image contained into the structure. Note that a number of functions will refuse to handle images which haven't been standardised through fp_img_standardize() (meaning the FP_IMG_V_FLIPPED , FP_IMG_H_FLIPPED and FP_IMG_COLORS_INVERTED should all be unset when the image needs to be analysed).