Paeth predicter, used by PNG filter type 4 The parameters are of type short, but should come from unsigned chars, the shorts are only needed to make t

out must be buffer big enough to contain uncompressed IDAT chunk data, and in must contain the full image. return value is error**/

search the index in the array, that has the largest value smaller than or equal to the given value, given array must be sorted (if no value is smaller

returns 1 if success, 0 if failure ==> nothing done*/

wpos = pos & (windowsize - 1)*/

write the lz77-encoded data, which has lit, len and dist codes, to compressed stream using huffman trees. tree_ll: the tree for lit and len codes. tre

in: Adam7 interlaced image, with no padding bits between scanlines, but between reduced images so that each reduced image starts at a byte. out: the

in: non-interlaced image with size w*h out: the same pixels, but re-ordered according to PNG's Adam7 interlacing, with no padding bits between scanli

Adds all lit/len and dist codes from the lists as huffman symbols. Does not add end code 256. expected_data_size is the uncompressed block size, used

Adds the bit lengths. */

Use fast compression to check which PNG filter strategy gives the smallest output. This allows to then do the slow and good compression only on that f

Performs a Boundary Package-Merge step. Puts a new chain in the given list. The new chain is, depending on the weights, a leaf or a combination of two

Returns the CRC of the bytes buf[0..len-1]. */

Calculates size of the part after the header and tree of an LZ77 block, in bits. */

Gives the exact size of the tree, in bits, as it will be encoded in DEFLATE. */

Does squeeze strategy where first the best possible lz77 is done, and then based on that data, block splitting is done. Parameters: see description of

Converts result of boundary package-merge to the bitlengths. The result in the last chain of the last list contains the amount of active leaves in eac

Finds next block to try to split, the largest of the available ones. The largest is chosen to make sure that if only a limited amount of blocks is req

Finds minimum of function f(i) where is is of type size_t, f(i) is of type double, i is in range start-end (excluding end). */

Performs the forward pass for "squeeze". Gets the most optimal length to reach every byte from a previous byte, using cost calculations. s: the Zopfli

Finds the minimum possible cost this cost model can return for valid length and distance symbols. */

Finds how long the match of scan and match is. Can be used to find how many bytes starting from scan, and from match, are equal. Returns the last byte

the tree representation used by the decoder. return value is error*/

Initializes each list with as lookahead chains the two leaves with lowest weights. */

Sets everything to 0. */

Keeps chunks with given names from the original png by literally copying them into the new png

Remove RGB information from pixels with alpha=0