Undoes intrapixel differencing */

Reduce RGB files to grayscale, with or without alpha * using the equation given in Poynton's ColorFAQ of 1998-01-04 at * <http://www.inforamp.net/~p

Scale rows of bit depth 16 down to 8 accurately */

Shift pixel values to take advantage of whole range. Pass the * true number of bits in bit_depth. The row should be packed * according to row_info

Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel, * without changing the actual values. Thus, if you had a row with * a bit depth o

Reverse the effects of png_do_shift. This routine merely shifts the * pixels back to their significant bits values. Thus, if you have * a row of b

Pick out the correct pixels for the interlace pass. * The basic idea here is to go through the row with a source * pointer and a destination pointer

Undoes intrapixel differencing */

Transform the data according to the user's wishes. The order of * transformations is significant. */

Utility to dump an unsigned value into a buffer, given a start pointer and * and end pointer (which should point just *beyond* the end of the buffer!

In the case of gamma transformations only do transformations on images where * the [file] gamma and screen_gamma are not close reciprocals, otherwise

currently required for png_image_write_* */ Initialize the write structure - general purpose utility. */

For the moment 'png_init_palette_transformations' and * 'png_init_rgb_transformations' only do some flag canceling optimizations. * The intent is th

The above gives exact (to 16 binary places) log2 values for 8-bit images, * for 16-bit images we use the most significant 8 bits of the 16-bit value

The following is for when the caller doesn't much care about the * result. */

What we do with the incoming data depends on what we were previously * doing before we ran out of data... */

Read any remaining signature bytes from the stream and compare them with * the correct PNG signature. It is possible that this routine is called *

Free all memory used in the read struct */

Read the entire image. If the image has an alpha channel or a tRNS * chunk, and you have called png_handle_alpha()[*], you will need to * initializ

Read and check the PNG file signature */

Modify the info structure to reflect the transformations. The * info should be updated so a PNG file could be written with it, * assuming the trans

Added to libpng-1.2.7 */

This function is called when the application wants to use another method * of handling errors and warnings. Note that the error function MUST NOT *

Expand grayscale images of less than 8-bit depth to 8 bits. */

Allow the application to select one or more row filters to use. */

This function is called when the application wants to use another method * of allocating and freeing memory. */

Chop 16-bit depth files to 8-bit depth */

Expand tRNS chunks to alpha channels. */

This function allows the application to supply new output functions for * libpng if standard C streams aren't being used. * * This function takes a

Initialize palette, background, etc, after transformations * are set, but before any reading takes place. This allows * the user to obtain a gamma-

Check a user supplied version number, called from both read and write * functions that create a png_struct. */

Write an IEND chunk */

Write the palette. We are careful not to trust png_color to be in the * correct order for PNG, so people can redefine it to any convenient * struct

Write the background chunk */

Write the cHRM chunk */

This is the API that calls the internal function above. */

Free any memory used in png_ptr struct without freeing the struct itself. */

Do the actual writing of a previously filtered row. */

Flush the current output buffers now */

Write a gAMA chunk */

Write the histogram */

Write an iCCP chunk */

Write the image. You only need to call this function once, even * if you are writing an interlaced image. */

Writes all the PNG information. This is the suggested way to use the * library. If you have a new chunk to add, make a function to write it, * and

Write the oFFs chunk */

Write the pCAL chunk (described in the PNG extensions document) */

Write the pHYs chunk */

Write the sBIT chunk */

Write the sCAL chunk */

Write a sPLT chunk */

Write a sRGB chunk */

Simple function to write the signature. If we have already written * the magic bytes of the signature, or more likely, the PNG stream is * being em

Initializes the row writing capability of libpng */

Write the tRNS chunk */

Function to free memory for zlib */