diff --git a/stb_image_resize.h b/stb_image_resize.h index bfed013..203f13b 100644 --- a/stb_image_resize.h +++ b/stb_image_resize.h @@ -22,7 +22,7 @@ input_pixels , in_w , in_h , 0, output_pixels, out_w, out_h, 0, num_channels , alpha_chan , 0, STBIR_EDGE_CLAMP) - WRAP/REFLECT/ZERO + // WRAP/REFLECT/ZERO FULL API See the "header file" section of the source for API documentation. @@ -629,11 +629,81 @@ static float stbir__srgb_uchar_to_linear_float[256] = { 0.982251f, 0.991102f, 1.0f }; +static float stbir__srgb_to_linear(float f) +{ + if (f <= 0.04045f) + return f / 12.92f; + else + return (float)pow((f + 0.055f) / 1.055f, 2.4f); +} + +static float stbir__linear_to_srgb(float f) +{ + if (f <= 0.0031308f) + return f * 12.92f; + else + return 1.055f * (float)pow(f, 1 / 2.4f) - 0.055f; +} + +#ifndef STBIR_NON_IEEE_FLOAT +// From https://gist.github.com/rygorous/2203834 + +typedef union +{ + stbir_uint32 u; + float f; + struct + { + stbir_uint32 Mantissa : 23; + stbir_uint32 Exponent : 8; + stbir_uint32 Sign : 1; + }; +} stbir__FP32; + +static const stbir_uint32 fp32_to_srgb8_tab4[104] = { + 0x0073000d, 0x007a000d, 0x0080000d, 0x0087000d, 0x008d000d, 0x0094000d, 0x009a000d, 0x00a1000d, + 0x00a7001a, 0x00b4001a, 0x00c1001a, 0x00ce001a, 0x00da001a, 0x00e7001a, 0x00f4001a, 0x0101001a, + 0x010e0033, 0x01280033, 0x01410033, 0x015b0033, 0x01750033, 0x018f0033, 0x01a80033, 0x01c20033, + 0x01dc0067, 0x020f0067, 0x02430067, 0x02760067, 0x02aa0067, 0x02dd0067, 0x03110067, 0x03440067, + 0x037800ce, 0x03df00ce, 0x044600ce, 0x04ad00ce, 0x051400ce, 0x057b00c5, 0x05dd00bc, 0x063b00b5, + 0x06970158, 0x07420142, 0x07e30130, 0x087b0120, 0x090b0112, 0x09940106, 0x0a1700fc, 0x0a9500f2, + 0x0b0f01cb, 0x0bf401ae, 0x0ccb0195, 0x0d950180, 0x0e56016e, 0x0f0d015e, 0x0fbc0150, 0x10630143, + 0x11070264, 0x1238023e, 0x1357021d, 0x14660201, 0x156601e9, 0x165a01d3, 0x174401c0, 0x182401af, + 0x18fe0331, 0x1a9602fe, 0x1c1502d2, 0x1d7e02ad, 0x1ed4028d, 0x201a0270, 0x21520256, 0x227d0240, + 0x239f0443, 0x25c003fe, 0x27bf03c4, 0x29a10392, 0x2b6a0367, 0x2d1d0341, 0x2ebe031f, 0x304d0300, + 0x31d105b0, 0x34a80555, 0x37520507, 0x39d504c5, 0x3c37048b, 0x3e7c0458, 0x40a8042a, 0x42bd0401, + 0x44c20798, 0x488e071e, 0x4c1c06b6, 0x4f76065d, 0x52a50610, 0x55ac05cc, 0x5892058f, 0x5b590559, + 0x5e0c0a23, 0x631c0980, 0x67db08f6, 0x6c55087f, 0x70940818, 0x74a007bd, 0x787d076c, 0x7c330723, +}; + +static stbir_uint8 stbir__linear_to_srgb_uchar(float in) +{ + static const stbir__FP32 almostone = { 0x3f7fffff }; // 1-eps + static const stbir__FP32 minval = { (127-13) << 23 }; + stbir_uint32 tab,bias,scale,t; + stbir__FP32 f; + + // Clamp to [2^(-13), 1-eps]; these two values map to 0 and 1, respectively. + // The tests are carefully written so that NaNs map to 0, same as in the reference + // implementation. + if (!(in > minval.f)) // written this way to catch NaNs + in = minval.f; + if (in > almostone.f) + in = almostone.f; + + // Do the table lookup and unpack bias, scale + f.f = in; + tab = fp32_to_srgb8_tab4[(f.u - minval.u) >> 20]; + bias = (tab >> 16) << 9; + scale = tab & 0xffff; + + // Grab next-highest mantissa bits and perform linear interpolation + t = (f.u >> 12) & 0xff; + return (unsigned char) ((bias + scale*t) >> 16); +} + +#else // sRGB transition values, scaled by 1<<28 -// note that if you only scaled by 1<<16, all the values would be 4K smaller, -// so [1] would be ~10, and so that would have around 5% error (10 +- 0.5) -// at the boundary between uint8 0 and 1. This also means that a 64K-entry table -// would have the same 5% error there. static int stbir__srgb_offset_to_linear_scaled[256] = { 0, 40738, 122216, 203693, 285170, 366648, 448125, 529603, @@ -670,118 +740,24 @@ static int stbir__srgb_offset_to_linear_scaled[256] = 250824112, 253132064, 255452368, 257785040, 260130080, 262487520, 264857376, 267239664, }; -static float stbir__srgb_to_linear(float f) -{ - if (f <= 0.04045f) - return f / 12.92f; - else - return (float)pow((f + 0.055f) / 1.055f, 2.4f); -} - -static float stbir__linear_to_srgb(float f) -{ - if (f <= 0.0031308f) - return f * 12.92f; - else - return 1.055f * (float)pow(f, 1 / 2.4f) - 0.055f; -} - -#ifndef STBIR_NON_IEEE_FLOAT - -// From https://gist.github.com/rygorous/2203834 - -typedef union -{ - stbir_uint32 u; - float f; - struct - { - stbir_uint32 Mantissa : 23; - stbir_uint32 Exponent : 8; - stbir_uint32 Sign : 1; - }; -} stbir__FP32; - -static const stbir_uint32 fp32_to_srgb8_tab3[64] = { - 0x0b0f01cb, 0x0bf401ae, 0x0ccb0195, 0x0d950180, 0x0e56016e, 0x0f0d015e, 0x0fbc0150, 0x10630143, - 0x11070264, 0x1238023e, 0x1357021d, 0x14660201, 0x156601e9, 0x165a01d3, 0x174401c0, 0x182401af, - 0x18fe0331, 0x1a9602fe, 0x1c1502d2, 0x1d7e02ad, 0x1ed4028d, 0x201a0270, 0x21520256, 0x227d0240, - 0x239f0443, 0x25c003fe, 0x27bf03c4, 0x29a10392, 0x2b6a0367, 0x2d1d0341, 0x2ebe031f, 0x304d0300, - 0x31d105b0, 0x34a80555, 0x37520507, 0x39d504c5, 0x3c37048b, 0x3e7c0458, 0x40a8042a, 0x42bd0401, - 0x44c20798, 0x488e071e, 0x4c1c06b6, 0x4f76065d, 0x52a50610, 0x55ac05cc, 0x5892058f, 0x5b590559, - 0x5e0c0a23, 0x631c0980, 0x67db08f6, 0x6c55087f, 0x70940818, 0x74a007bd, 0x787d076c, 0x7c330723, - 0x06970158, 0x07420142, 0x07e30130, 0x087b0120, 0x090b0112, 0x09940106, 0x0a1700fc, 0x0a9500f2, -}; - -static stbir_uint8 stbir__linear_to_srgb_uchar(float in) -{ - static const stbir__FP32 almostone = { 0x3f7fffff }; // 1-eps - static const stbir__FP32 lutthresh = { 0x3b800000 }; // 2^(-8) - static const stbir__FP32 linearsc = { 0x454c5d00 }; - static const stbir__FP32 float2int = { (127 + 23) << 23 }; - stbir__FP32 f; - - // Clamp to [0, 1-eps]; these two values map to 0 and 1, respectively. - // The tests are carefully written so that NaNs map to 0, same as in the reference - // implementation. - if (!(in > 0.0f)) // written this way to catch NaNs - in = 0.0f; - if (in > almostone.f) - in = almostone.f; - - // Check which region this value falls into - f.f = in; - if (f.f < lutthresh.f) // linear region - { - f.f *= linearsc.f; - f.f += float2int.f; // use "magic value" to get float->int with rounding. - return (stbir_uint8)(f.u & 255); - } - else // non-linear region - { - // Unpack bias, scale from table - stbir_uint32 tab = fp32_to_srgb8_tab3[(f.u >> 20) & 63]; - stbir_uint32 bias = (tab >> 16) << 9; - stbir_uint32 scale = tab & 0xffff; - - // Grab next-highest mantissa bits and perform linear interpolation - stbir_uint32 t = (f.u >> 12) & 0xff; - return (stbir_uint8)((bias + scale*t) >> 16); - } -} - -#else - -// Used as a starting point to save time in the binary search in stbir__linear_to_srgb_uchar. -static stbir_uint8 stbr__linear_uchar_to_srgb_uchar[] = { - 0, 12, 21, 28, 33, 38, 42, 46, 49, 52, 55, 58, 61, 63, 66, 68, 70, 73, 75, 77, 79, 81, 82, 84, 86, 88, 89, 91, 93, 94, - 96, 97, 99, 100, 102, 103, 104, 106, 107, 109, 110, 111, 112, 114, 115, 116, 117, 118, 120, 121, 122, 123, 124, 125, 126, - 127, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 142, 143, 144, 145, 146, 147, 148, 149, 150, - 151, 151, 152, 153, 154, 155, 156, 157, 157, 158, 159, 160, 161, 161, 162, 163, 164, 165, 165, 166, 167, 168, 168, 169, - 170, 171, 171, 172, 173, 174, 174, 175, 176, 176, 177, 178, 179, 179, 180, 181, 181, 182, 183, 183, 184, 185, 185, 186, - 187, 187, 188, 189, 189, 190, 191, 191, 192, 193, 193, 194, 194, 195, 196, 196, 197, 197, 198, 199, 199, 200, 201, 201, - 202, 202, 203, 204, 204, 205, 205, 206, 206, 207, 208, 208, 209, 209, 210, 210, 211, 212, 212, 213, 213, 214, 214, 215, - 215, 216, 217, 217, 218, 218, 219, 219, 220, 220, 221, 221, 222, 222, 223, 223, 224, 224, 225, 226, 226, 227, 227, 228, - 228, 229, 229, 230, 230, 231, 231, 232, 232, 233, 233, 234, 234, 235, 235, 236, 236, 237, 237, 237, 238, 238, 239, 239, - 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 245, 246, 246, 247, 247, 248, 248, 249, 249, 250, 250, 251, - 251, 251, 252, 252, 253, 253, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 -}; - static stbir_uint8 stbir__linear_to_srgb_uchar(float f) { int x = (int) (f * (1 << 28)); // has headroom so you don't need to clamp - int v = stbr__linear_uchar_to_srgb_uchar[(int)(f * 255)]; // Make a guess at the value with a table. + int v = 0; int i; // Refine the guess with a short binary search. - i = v + 8; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; - i = v + 4; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; - i = v + 2; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; - i = v + 1; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 128; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 64; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 32; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 16; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 8; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 4; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 2; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; + i = v + 1; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i; return (stbir_uint8) v; } - #endif static float stbir__filter_trapezoid(float x, float scale)