From eb84b2179b059aef3a0ceb5fc9a8b66b9de81234 Mon Sep 17 00:00:00 2001 From: Socks the Fox Date: Mon, 18 Jan 2016 10:42:41 -0600 Subject: [PATCH] Initial 16 bit per channel PNG support --- stb_image.h | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 113 insertions(+), 20 deletions(-) diff --git a/stb_image.h b/stb_image.h index be25097..daa47ae 100644 --- a/stb_image.h +++ b/stb_image.h @@ -3938,6 +3938,7 @@ typedef struct { stbi__context *s; stbi_uc *idata, *expanded, *out; + int depth; } stbi__png; @@ -3977,14 +3978,19 @@ static stbi_uc stbi__depth_scale_table[9] = { 0, 0xff, 0x55, 0, 0x11, 0,0,0, 0x0 // create the png data from post-deflated data static int stbi__create_png_image_raw(stbi__png *a, stbi_uc *raw, stbi__uint32 raw_len, int out_n, stbi__uint32 x, stbi__uint32 y, int depth, int color) { + int bytes = (depth == 16? 2 : 1); stbi__context *s = a->s; - stbi__uint32 i,j,stride = x*out_n; + stbi__uint32 i,j,stride = x*out_n*bytes; stbi__uint32 img_len, img_width_bytes; int k; int img_n = s->img_n; // copy it into a local for later + int output_bytes = out_n*bytes; + int filter_bytes = img_n*bytes; + int width = x; + STBI_ASSERT(out_n == s->img_n || out_n == s->img_n+1); - a->out = (stbi_uc *) stbi__malloc(x * y * out_n); // extra bytes to write off the end into + a->out = (stbi_uc *) stbi__malloc(x * y * output_bytes); // extra bytes to write off the end into if (!a->out) return stbi__err("outofmem", "Out of memory"); img_width_bytes = (((img_n * x * depth) + 7) >> 3); @@ -3999,8 +4005,7 @@ static int stbi__create_png_image_raw(stbi__png *a, stbi_uc *raw, stbi__uint32 r stbi_uc *cur = a->out + stride*j; stbi_uc *prior = cur - stride; int filter = *raw++; - int filter_bytes = img_n; - int width = x; + if (filter > 4) return stbi__err("invalid filter","Corrupt PNG"); @@ -4033,6 +4038,14 @@ static int stbi__create_png_image_raw(stbi__png *a, stbi_uc *raw, stbi__uint32 r raw += img_n; cur += out_n; prior += out_n; + } else if (depth == 16) { + if (img_n != out_n) { + cur[filter_bytes] = 255; // first pixel top byte + cur[filter_bytes+1] = 255; // first pixel bottom byte + } + raw += filter_bytes; + cur += output_bytes; + prior += output_bytes; } else { raw += 1; cur += 1; @@ -4041,7 +4054,7 @@ static int stbi__create_png_image_raw(stbi__png *a, stbi_uc *raw, stbi__uint32 r // this is a little gross, so that we don't switch per-pixel or per-component if (depth < 8 || img_n == out_n) { - int nk = (width - 1)*img_n; + int nk = (width - 1)*filter_bytes; #define CASE(f) \ case f: \ for (k=0; k < nk; ++k) @@ -4061,18 +4074,27 @@ static int stbi__create_png_image_raw(stbi__png *a, stbi_uc *raw, stbi__uint32 r STBI_ASSERT(img_n+1 == out_n); #define CASE(f) \ case f: \ - for (i=x-1; i >= 1; --i, cur[img_n]=255,raw+=img_n,cur+=out_n,prior+=out_n) \ - for (k=0; k < img_n; ++k) + for (i=x-1; i >= 1; --i, cur[filter_bytes]=255,raw+=filter_bytes,cur+=output_bytes,prior+=output_bytes) \ + for (k=0; k < filter_bytes; ++k) switch (filter) { CASE(STBI__F_none) cur[k] = raw[k]; break; - CASE(STBI__F_sub) cur[k] = STBI__BYTECAST(raw[k] + cur[k-out_n]); break; + CASE(STBI__F_sub) cur[k] = STBI__BYTECAST(raw[k] + cur[k- output_bytes]); break; CASE(STBI__F_up) cur[k] = STBI__BYTECAST(raw[k] + prior[k]); break; - CASE(STBI__F_avg) cur[k] = STBI__BYTECAST(raw[k] + ((prior[k] + cur[k-out_n])>>1)); break; - CASE(STBI__F_paeth) cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k-out_n],prior[k],prior[k-out_n])); break; - CASE(STBI__F_avg_first) cur[k] = STBI__BYTECAST(raw[k] + (cur[k-out_n] >> 1)); break; - CASE(STBI__F_paeth_first) cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k-out_n],0,0)); break; + CASE(STBI__F_avg) cur[k] = STBI__BYTECAST(raw[k] + ((prior[k] + cur[k- output_bytes])>>1)); break; + CASE(STBI__F_paeth) cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k- output_bytes],prior[k],prior[k- output_bytes])); break; + CASE(STBI__F_avg_first) cur[k] = STBI__BYTECAST(raw[k] + (cur[k- output_bytes] >> 1)); break; + CASE(STBI__F_paeth_first) cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k- output_bytes],0,0)); break; } #undef CASE + + // the loop above sets the high byte of the pixels' alpha, but for + // 16 bit png files we also need the low byte set. we'll do that here. + if (depth == 16) { + cur = a->out + stride*j; // start at the beginning of the row again + for (i=0; i < x; ++i,cur+=output_bytes) { + cur[filter_bytes+1] = 255; + } + } } } @@ -4148,6 +4170,17 @@ static int stbi__create_png_image_raw(stbi__png *a, stbi_uc *raw, stbi__uint32 r } } } + } else if (depth == 16) { + // force the image data from big-endian to platform-native. + // this is done in a separate pass due to the decoding relying + // on the data being untouched, but could probably be done + // per-line during decode if care is taken. + stbi_uc *cur = a->out; + stbi__uint16 *cur16 = (stbi__uint16*)cur; + + for(i=0; i < x*y*out_n; ++i,cur16++,cur+=2) { + *cur16 = (cur[0] << 8) | cur[1]; + } } return 1; @@ -4220,6 +4253,31 @@ static int stbi__compute_transparency(stbi__png *z, stbi_uc tc[3], int out_n) return 1; } +static int stbi__compute_transparency16(stbi__png *z, stbi__uint16 tc[3], int out_n) +{ + stbi__context *s = z->s; + stbi__uint32 i, pixel_count = s->img_x * s->img_y; + stbi__uint16 *p = (stbi__uint16*) z->out; + + // compute color-based transparency, assuming we've + // already got 65535 as the alpha value in the output + STBI_ASSERT(out_n == 2 || out_n == 4); + + if (out_n == 2) { + for (i = 0; i < pixel_count; ++i) { + p[1] = (p[0] == tc[0] ? 0 : 65535); + p += 2; + } + } else { + for (i = 0; i < pixel_count; ++i) { + if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2]) + p[3] = 0; + p += 4; + } + } + return 1; +} + static int stbi__expand_png_palette(stbi__png *a, stbi_uc *palette, int len, int pal_img_n) { stbi__uint32 i, pixel_count = a->s->img_x * a->s->img_y; @@ -4257,6 +4315,26 @@ static int stbi__expand_png_palette(stbi__png *a, stbi_uc *palette, int len, int return 1; } +static int stbi__reduce_png(stbi__png *p) +{ + int i; + int img_len = p->s->img_x * p->s->img_y * p->s->img_out_n; + stbi_uc *reduced; + stbi__uint16 *orig = (stbi__uint16*)p->out; + + if (p->depth != 16) return 1; // don't need to do anything if not 16-bit data + + reduced = (stbi_uc *)stbi__malloc(img_len); + if (p == NULL) return stbi__err("outofmem", "Out of memory"); + + for (i = 0; i < img_len; ++i) reduced[i] = (stbi_uc)((orig[i] >> 8) & 0xFF); // top half of each byte is a decent approx of 16->8 bit scaling + + p->out = reduced; + STBI_FREE(orig); + + return 1; +} + static int stbi__unpremultiply_on_load = 0; static int stbi__de_iphone_flag = 0; @@ -4318,8 +4396,9 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp) { stbi_uc palette[1024], pal_img_n=0; stbi_uc has_trans=0, tc[3]; + stbi__uint16 tc16[3]; stbi__uint32 ioff=0, idata_limit=0, i, pal_len=0; - int first=1,k,interlace=0, color=0, depth=0, is_iphone=0; + int first=1,k,interlace=0, color=0, is_iphone=0; stbi__context *s = z->s; z->expanded = NULL; @@ -4344,8 +4423,9 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp) if (c.length != 13) return stbi__err("bad IHDR len","Corrupt PNG"); s->img_x = stbi__get32be(s); if (s->img_x > (1 << 24)) return stbi__err("too large","Very large image (corrupt?)"); s->img_y = stbi__get32be(s); if (s->img_y > (1 << 24)) return stbi__err("too large","Very large image (corrupt?)"); - depth = stbi__get8(s); if (depth != 1 && depth != 2 && depth != 4 && depth != 8) return stbi__err("1/2/4/8-bit only","PNG not supported: 1/2/4/8-bit only"); + z->depth = stbi__get8(s); if (z->depth != 1 && z->depth != 2 && z->depth != 4 && z->depth != 8 && z->depth != 16) return stbi__err("1/2/4/8/16-bit only","PNG not supported: 1/2/4/8/16-bit only"); color = stbi__get8(s); if (color > 6) return stbi__err("bad ctype","Corrupt PNG"); + if (color == 3 && z->depth == 16) return stbi__err("bad ctype","Corrupt PNG"); if (color == 3) pal_img_n = 3; else if (color & 1) return stbi__err("bad ctype","Corrupt PNG"); comp = stbi__get8(s); if (comp) return stbi__err("bad comp method","Corrupt PNG"); filter= stbi__get8(s); if (filter) return stbi__err("bad filter method","Corrupt PNG"); @@ -4393,8 +4473,11 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp) if (!(s->img_n & 1)) return stbi__err("tRNS with alpha","Corrupt PNG"); if (c.length != (stbi__uint32) s->img_n*2) return stbi__err("bad tRNS len","Corrupt PNG"); has_trans = 1; - for (k=0; k < s->img_n; ++k) - tc[k] = (stbi_uc) (stbi__get16be(s) & 255) * stbi__depth_scale_table[depth]; // non 8-bit images will be larger + if (z->depth == 16) { + for (k = 0; k < s->img_n; ++k) tc16[k] = stbi__get16be(s); // copy the values as-is + } else { + for (k = 0; k < s->img_n; ++k) tc[k] = (stbi_uc)(stbi__get16be(s) & 255) * stbi__depth_scale_table[z->depth]; // non 8-bit images will be larger + } } break; } @@ -4424,7 +4507,7 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp) if (scan != STBI__SCAN_load) return 1; if (z->idata == NULL) return stbi__err("no IDAT","Corrupt PNG"); // initial guess for decoded data size to avoid unnecessary reallocs - bpl = (s->img_x * depth + 7) / 8; // bytes per line, per component + bpl = (s->img_x * z->depth + 7) / 8; // bytes per line, per component raw_len = bpl * s->img_y * s->img_n /* pixels */ + s->img_y /* filter mode per row */; z->expanded = (stbi_uc *) stbi_zlib_decode_malloc_guesssize_headerflag((char *) z->idata, ioff, raw_len, (int *) &raw_len, !is_iphone); if (z->expanded == NULL) return 0; // zlib should set error @@ -4433,9 +4516,14 @@ static int stbi__parse_png_file(stbi__png *z, int scan, int req_comp) s->img_out_n = s->img_n+1; else s->img_out_n = s->img_n; - if (!stbi__create_png_image(z, z->expanded, raw_len, s->img_out_n, depth, color, interlace)) return 0; - if (has_trans) - if (!stbi__compute_transparency(z, tc, s->img_out_n)) return 0; + if (!stbi__create_png_image(z, z->expanded, raw_len, s->img_out_n, z->depth, color, interlace)) return 0; + if (has_trans) { + if (z->depth == 16) { + if (!stbi__compute_transparency16(z, tc16, s->img_out_n)) return 0; + } else { + if (!stbi__compute_transparency(z, tc, s->img_out_n)) return 0; + } + } if (is_iphone && stbi__de_iphone_flag && s->img_out_n > 2) stbi__de_iphone(z); if (pal_img_n) { @@ -4477,6 +4565,11 @@ static unsigned char *stbi__do_png(stbi__png *p, int *x, int *y, int *n, int req unsigned char *result=NULL; if (req_comp < 0 || req_comp > 4) return stbi__errpuc("bad req_comp", "Internal error"); if (stbi__parse_png_file(p, STBI__SCAN_load, req_comp)) { + if (p->depth == 16) { + if (!stbi__reduce_png(p)) { + return result; + } + } result = p->out; p->out = NULL; if (req_comp && req_comp != p->s->img_out_n) {