This function was added to libpng-1.0.7 */

NOTE: this function expects the *inverse* of the overall gamma transformation * required. */

We build the 8- or 16-bit gamma tables here. Note that for 16-bit * tables, we don't make a full table if we are reducing to 8-bit in * the future.

This is the check going the other way. The XYZ is modified to normalize it * (another side-effect) and the xy chromaticities are returned. */

Compare the CRC stored in the PNG file with that calculated by libpng from * the data it has read thus far. */

This function is called when there is a warning, but the library thinks * it can continue anyway. Replacement functions don't have to do anything *

Replace any alpha or transparency with the supplied background color. * "background" is already in the screen gamma, while "background_1" is * at a

Encode the alpha channel to the output gamma (the input channel is always * linear.) Called only with color types that have an alpha channel. Needs

If the bit depth is 8 and the color type is not a palette type expand the * whole row to 16 bits. Has no effect otherwise. */

Expands a palette row to an RGB or RGBA row depending * upon whether you supply trans and num_trans. */

Pack pixels into bytes. Pass the true bit depth in bit_depth. The * row_info bit depth should be 8 (one pixel per byte). The channels * should be

Add filler channel if we have RGB color */

Undoes intrapixel differencing, * NOTE: this is apparently only supported in the 'sequential' reader. */

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

Performs 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

The following return the library version as a short string in the * format 1.0.0 through 99.99.99zz. To get the version of *.h files * used with yo

FLOATING POINT */

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 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 */

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

Expand tRNS chunks to alpha channels. */

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 */