[hackers] [farbfeld] ff2png: Export 16-Bit RGBA PNG's so we don't lose data || FRIGN

[git]

commit 8c161ba22e717a82733a6e4192138d153615d3dc
Author:     FRIGN <d...@frign.de>
AuthorDate: Mon Jan 4 17:44:10 2016 +0100
Commit:     FRIGN <d...@frign.de>
CommitDate: Mon Jan 4 17:44:10 2016 +0100

    ff2png: Export 16-Bit RGBA PNG's so we don't lose data

diff --git a/ff2png.c b/ff2png.c
index 8cded89..ad39720 100644
--- a/ff2png.c
+++ b/ff2png.c
@@ -15,8 +15,8 @@ main(int argc, char *argv[])
 {
        png_structp png_struct_p;
        png_infop png_info_p;
-       uint8_t hdr[16], *png_row;
-       uint16_t tmp16;
+       uint8_t hdr[16];
+       uint16_t tmp16, *png_row;
        png_uint_32 width, height, i;
        png_size_t png_row_len, j;
 
@@ -46,12 +46,12 @@ main(int argc, char *argv[])
                return 1;
        }
        png_init_io(png_struct_p, stdout);
-       png_set_IHDR(png_struct_p, png_info_p, width, height, 8, 
PNG_COLOR_TYPE_RGB_ALPHA,
+       png_set_IHDR(png_struct_p, png_info_p, width, height, 16, 
PNG_COLOR_TYPE_RGB_ALPHA,
                     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, 
PNG_FILTER_TYPE_BASE);
        png_write_info(png_struct_p, png_info_p);
 
        /* write rows */
-       png_row_len = strlen("RGBA") * width * sizeof(uint8_t);
+       png_row_len = strlen("RGBA") * width * sizeof(uint16_t);
        png_row = malloc(png_row_len);
        if (!png_row) {
                fprintf(stderr, "failed to allocate row-buffer\n");
@@ -59,15 +59,14 @@ main(int argc, char *argv[])
        }
 
        for (i = 0; i < height; ++i) {
-               for (j = 0; j < png_row_len; ++j) {
+               for (j = 0; j < png_row_len / sizeof(uint16_t); ++j) {
                        if (fread(&tmp16, 1, sizeof(uint16_t), stdin) != 
sizeof(uint16_t)) {
                                fprintf(stderr, "unexpected EOF or row-skew\n");
                                return 1;
                        }
-                       /* ((2^16-1) / 255) == 257 */
-                       png_row[j] = (uint8_t)(ntohs(tmp16) / 257);
+                       png_row[j] = tmp16;
                }
-               png_write_row(png_struct_p, png_row);
+               png_write_row(png_struct_p, (uint8_t *)png_row);
        }
        png_write_end(png_struct_p, NULL);