libultrahdr: correct srgb, p3 calculations and jpeg yuv handling am: 0db53ee3c9 (5ad0df9b) · Commits · e / os / platform_frameworks_native

libs/ultrahdr/gainmapmath.cpp

+132 −17

Original line number	Diff line number	Diff line
		@@ -119,34 +119,39 @@ static float clampPixelFloat(float value) {
		return (value < 0.0f) ? 0.0f : (value > kMaxPixelFloat) ? kMaxPixelFloat : value;
		}

		// See IEC 61966-2-1, Equation F.7.
		// See IEC 61966-2-1/Amd 1:2003, Equation F.7.
		static const float kSrgbR = 0.2126f, kSrgbG = 0.7152f, kSrgbB = 0.0722f;

		float srgbLuminance(Color e) {
		return kSrgbR * e.r + kSrgbG * e.g + kSrgbB * e.b;
		}

		// See ECMA TR/98, Section 7.
		static const float kSrgbRCr = 1.402f, kSrgbGCb = 0.34414f, kSrgbGCr = 0.71414f, kSrgbBCb = 1.772f;
		// See ITU-R BT.709-6, Section 3.
		// Uses the same coefficients for deriving luma signal as
		// IEC 61966-2-1/Amd 1:2003 states for luminance, so we reuse the luminance
		// function above.
		static const float kSrgbCb = 1.8556f, kSrgbCr = 1.5748f;

		Color srgbYuvToRgb(Color e_gamma) {
		return {{{ clampPixelFloat(e_gamma.y + kSrgbRCr * e_gamma.v),
		clampPixelFloat(e_gamma.y - kSrgbGCb * e_gamma.u - kSrgbGCr * e_gamma.v),
		clampPixelFloat(e_gamma.y + kSrgbBCb * e_gamma.u) }}};
		Color srgbRgbToYuv(Color e_gamma) {
		float y_gamma = srgbLuminance(e_gamma);
		return {{{ y_gamma,
		(e_gamma.b - y_gamma) / kSrgbCb,
		(e_gamma.r - y_gamma) / kSrgbCr }}};
		}

		// See ECMA TR/98, Section 7.
		static const float kSrgbYR = 0.299f, kSrgbYG = 0.587f, kSrgbYB = 0.114f;
		static const float kSrgbUR = -0.1687f, kSrgbUG = -0.3313f, kSrgbUB = 0.5f;
		static const float kSrgbVR = 0.5f, kSrgbVG = -0.4187f, kSrgbVB = -0.0813f;
		// See ITU-R BT.709-6, Section 3.
		// Same derivation to BT.2100's YUV->RGB, below. Similar to srgbRgbToYuv, we
		// can reuse the luminance coefficients since they are the same.
		static const float kSrgbGCb = kSrgbB * kSrgbCb / kSrgbG;
		static const float kSrgbGCr = kSrgbR * kSrgbCr / kSrgbG;

		Color srgbRgbToYuv(Color e_gamma) {
		return {{{ kSrgbYR * e_gamma.r + kSrgbYG * e_gamma.g + kSrgbYB * e_gamma.b,
		kSrgbUR * e_gamma.r + kSrgbUG * e_gamma.g + kSrgbUB * e_gamma.b,
		kSrgbVR * e_gamma.r + kSrgbVG * e_gamma.g + kSrgbVB * e_gamma.b }}};
		Color srgbYuvToRgb(Color e_gamma) {
		return {{{ clampPixelFloat(e_gamma.y + kSrgbCr * e_gamma.v),
		clampPixelFloat(e_gamma.y - kSrgbGCb * e_gamma.u - kSrgbGCr * e_gamma.v),
		clampPixelFloat(e_gamma.y + kSrgbCb * e_gamma.u) }}};
		}

		// See IEC 61966-2-1, Equations F.5 and F.6.
		// See IEC 61966-2-1/Amd 1:2003, Equations F.5 and F.6.
		float srgbInvOetf(float e_gamma) {
		if (e_gamma <= 0.04045f) {
		return e_gamma / 12.92f;
		@@ -178,13 +183,38 @@ Color srgbInvOetfLUT(Color e_gamma) {
		////////////////////////////////////////////////////////////////////////////////
		// Display-P3 transformations

		// See SMPTE EG 432-1, Table 7-2.
		// See SMPTE EG 432-1, Equation 7-8.
		static const float kP3R = 0.20949f, kP3G = 0.72160f, kP3B = 0.06891f;

		float p3Luminance(Color e) {
		return kP3R * e.r + kP3G * e.g + kP3B * e.b;
		}

		// See ITU-R BT.601-7, Sections 2.5.1 and 2.5.2.
		// Unfortunately, calculation of luma signal differs from calculation of
		// luminance for Display-P3, so we can't reuse p3Luminance here.
		static const float kP3YR = 0.299f, kP3YG = 0.587f, kP3YB = 0.114f;
		static const float kP3Cb = 1.772f, kP3Cr = 1.402f;

		Color p3RgbToYuv(Color e_gamma) {
		float y_gamma = kP3YR * e_gamma.r + kP3YG * e_gamma.g + kP3YB * e_gamma.b;
		return {{{ y_gamma,
		(e_gamma.b - y_gamma) / kP3Cb,
		(e_gamma.r - y_gamma) / kP3Cr }}};
		}

		// See ITU-R BT.601-7, Sections 2.5.1 and 2.5.2.
		// Same derivation to BT.2100's YUV->RGB, below. Similar to p3RgbToYuv, we must
		// use luma signal coefficients rather than the luminance coefficients.
		static const float kP3GCb = kP3YB * kP3Cb / kP3YG;
		static const float kP3GCr = kP3YR * kP3Cr / kP3YG;

		Color p3YuvToRgb(Color e_gamma) {
		return {{{ clampPixelFloat(e_gamma.y + kP3Cr * e_gamma.v),
		clampPixelFloat(e_gamma.y - kP3GCb * e_gamma.u - kP3GCr * e_gamma.v),
		clampPixelFloat(e_gamma.y + kP3Cb * e_gamma.u) }}};
		}


		////////////////////////////////////////////////////////////////////////////////
		// BT.2100 transformations - according to ITU-R BT.2100-2
		@@ -197,6 +227,8 @@ float bt2100Luminance(Color e) {
		}

		// See ITU-R BT.2100-2, Table 6, Derivation of colour difference signals.
		// BT.2100 uses the same coefficients for calculating luma signal and luminance,
		// so we reuse the luminance function here.
		static const float kBt2100Cb = 1.8814f, kBt2100Cr = 1.4746f;

		Color bt2100RgbToYuv(Color e_gamma) {
		@@ -206,6 +238,10 @@ Color bt2100RgbToYuv(Color e_gamma) {
		(e_gamma.r - y_gamma) / kBt2100Cr }}};
		}

		// See ITU-R BT.2100-2, Table 6, Derivation of colour difference signals.
		//
		// Similar to bt2100RgbToYuv above, we can reuse the luminance coefficients.
		//
		// Derived by inversing bt2100RgbToYuv. The derivation for R and B are pretty
		// straight forward; we just invert the formulas for U and V above. But deriving
		// the formula for G is a bit more complicated:
		@@ -440,6 +476,85 @@ ColorTransformFn getHdrConversionFn(ultrahdr_color_gamut sdr_gamut,
		}
		}

		// All of these conversions are derived from the respective input YUV->RGB conversion followed by
		// the RGB->YUV for the receiving encoding. They are consistent with the RGB<->YUV functions in this
		// file, given that we uses BT.709 encoding for sRGB and BT.601 encoding for Display-P3, to match
		// DataSpace.

		Color yuv709To601(Color e_gamma) {
		return {{{ 1.0f * e_gamma.y + 0.101579f * e_gamma.u + 0.196076f * e_gamma.v,
		0.0f * e_gamma.y + 0.989854f * e_gamma.u + -0.110653f * e_gamma.v,
		0.0f * e_gamma.y + -0.072453f * e_gamma.u + 0.983398f * e_gamma.v }}};
		}

		Color yuv709To2100(Color e_gamma) {
		return {{{ 1.0f * e_gamma.y + -0.016969f * e_gamma.u + 0.096312f * e_gamma.v,
		0.0f * e_gamma.y + 0.995306f * e_gamma.u + -0.051192f * e_gamma.v,
		0.0f * e_gamma.y + 0.011507f * e_gamma.u + 1.002637f * e_gamma.v }}};
		}

		Color yuv601To709(Color e_gamma) {
		return {{{ 1.0f * e_gamma.y + -0.118188f * e_gamma.u + -0.212685f * e_gamma.v,
		0.0f * e_gamma.y + 1.018640f * e_gamma.u + 0.114618f * e_gamma.v,
		0.0f * e_gamma.y + 0.075049f * e_gamma.u + 1.025327f * e_gamma.v }}};
		}

		Color yuv601To2100(Color e_gamma) {
		return {{{ 1.0f * e_gamma.y + -0.128245f * e_gamma.u + -0.115879f * e_gamma.v,
		0.0f * e_gamma.y + 1.010016f * e_gamma.u + 0.061592f * e_gamma.v,
		0.0f * e_gamma.y + 0.086969f * e_gamma.u + 1.029350f * e_gamma.v }}};
		}

		Color yuv2100To709(Color e_gamma) {
		return {{{ 1.0f * e_gamma.y + 0.018149f * e_gamma.u + -0.095132f * e_gamma.v,
		0.0f * e_gamma.y + 1.004123f * e_gamma.u + 0.051267f * e_gamma.v,
		0.0f * e_gamma.y + -0.011524f * e_gamma.u + 0.996782f * e_gamma.v }}};
		}

		Color yuv2100To601(Color e_gamma) {
		return {{{ 1.0f * e_gamma.y + 0.117887f * e_gamma.u + 0.105521f * e_gamma.v,
		0.0f * e_gamma.y + 0.995211f * e_gamma.u + -0.059549f * e_gamma.v,
		0.0f * e_gamma.y + -0.084085f * e_gamma.u + 0.976518f * e_gamma.v }}};
		}

		void transformYuv420(jr_uncompressed_ptr image, size_t x_chroma, size_t y_chroma,
		ColorTransformFn fn) {
		Color yuv1 = getYuv420Pixel(image, x_chroma * 2, y_chroma * 2 );
		Color yuv2 = getYuv420Pixel(image, x_chroma * 2 + 1, y_chroma * 2 );
		Color yuv3 = getYuv420Pixel(image, x_chroma * 2, y_chroma * 2 + 1);
		Color yuv4 = getYuv420Pixel(image, x_chroma * 2 + 1, y_chroma * 2 + 1);

		yuv1 = fn(yuv1);
		yuv2 = fn(yuv2);
		yuv3 = fn(yuv3);
		yuv4 = fn(yuv4);

		Color new_uv = (yuv1 + yuv2 + yuv3 + yuv4) / 4.0f;

		size_t pixel_y1_idx = x_chroma * 2 + y_chroma * 2 * image->width;
		size_t pixel_y2_idx = (x_chroma * 2 + 1) + y_chroma * 2 * image->width;
		size_t pixel_y3_idx = x_chroma * 2 + (y_chroma * 2 + 1) * image->width;
		size_t pixel_y4_idx = (x_chroma * 2 + 1) + (y_chroma * 2 + 1) * image->width;

		uint8_t& y1_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y1_idx];
		uint8_t& y2_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y2_idx];
		uint8_t& y3_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y3_idx];
		uint8_t& y4_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_y4_idx];

		size_t pixel_count = image->width * image->height;
		size_t pixel_uv_idx = x_chroma + y_chroma * (image->width / 2);

		uint8_t& u_uint = reinterpret_cast<uint8_t*>(image->data)[pixel_count + pixel_uv_idx];
		uint8_t& v_uint = reinterpret_cast<uint8_t>(image->data)[pixel_count 5 / 4 + pixel_uv_idx];

		y1_uint = static_cast<uint8_t>(floor(yuv1.y * 255.0f + 0.5f));
		y2_uint = static_cast<uint8_t>(floor(yuv2.y * 255.0f + 0.5f));
		y3_uint = static_cast<uint8_t>(floor(yuv3.y * 255.0f + 0.5f));
		y4_uint = static_cast<uint8_t>(floor(yuv4.y * 255.0f + 0.5f));

		u_uint = static_cast<uint8_t>(floor(new_uv.u * 255.0f + 128.0f + 0.5f));
		v_uint = static_cast<uint8_t>(floor(new_uv.v * 255.0f + 128.0f + 0.5f));
		}

		////////////////////////////////////////////////////////////////////////////////
		// Gain map calculations

libs/ultrahdr/icc.cpp

+94 −2

Original line number	Diff line number	Diff line
		@@ -14,6 +14,10 @@
		* limitations under the License.
		*/

		#ifndef USE_BIG_ENDIAN
		#define USE_BIG_ENDIAN true
		#endif

		#include <ultrahdr/icc.h>
		#include <ultrahdr/gainmapmath.h>
		#include <vector>
		@@ -540,13 +544,21 @@ sp<DataStruct> IccHelper::writeIccProfile(ultrahdr_transfer_function tf,
		size_t tag_table_size = kICCTagTableEntrySize * tags.size();
		size_t profile_size = kICCHeaderSize + tag_table_size + tag_data_size;

		sp<DataStruct> dataStruct = sp<DataStruct>::make(profile_size + kICCIdentifierSize);

		// Write identifier, chunk count, and chunk ID
		if (!dataStruct->write(kICCIdentifier, sizeof(kICCIdentifier)) \|\|
		!dataStruct->write8(1) \|\| !dataStruct->write8(1)) {
		ALOGE("writeIccProfile(): error in identifier");
		return dataStruct;
		}

		// Write the header.
		header.data_color_space = Endian_SwapBE32(Signature_RGB);
		header.pcs = Endian_SwapBE32(tf == ULTRAHDR_TF_PQ ? Signature_Lab : Signature_XYZ);
		header.size = Endian_SwapBE32(profile_size);
		header.tag_count = Endian_SwapBE32(tags.size());

		sp<DataStruct> dataStruct = sp<DataStruct>::make(profile_size);
		if (!dataStruct->write(&header, sizeof(header))) {
		ALOGE("writeIccProfile(): error in header");
		return dataStruct;
		@@ -582,4 +594,84 @@ sp<DataStruct> IccHelper::writeIccProfile(ultrahdr_transfer_function tf,
		return dataStruct;
		}

		bool IccHelper::tagsEqualToMatrix(const Matrix3x3& matrix,
		const uint8_t* red_tag,
		const uint8_t* green_tag,
		const uint8_t* blue_tag) {
		sp<DataStruct> red_tag_test = write_xyz_tag(matrix.vals[0][0], matrix.vals[1][0],
		matrix.vals[2][0]);
		sp<DataStruct> green_tag_test = write_xyz_tag(matrix.vals[0][1], matrix.vals[1][1],
		matrix.vals[2][1]);
		sp<DataStruct> blue_tag_test = write_xyz_tag(matrix.vals[0][2], matrix.vals[1][2],
		matrix.vals[2][2]);
		return memcmp(red_tag, red_tag_test->getData(), kColorantTagSize) == 0 &&
		memcmp(green_tag, green_tag_test->getData(), kColorantTagSize) == 0 &&
		memcmp(blue_tag, blue_tag_test->getData(), kColorantTagSize) == 0;
		}

		ultrahdr_color_gamut IccHelper::readIccColorGamut(void* icc_data, size_t icc_size) {
		// Each tag table entry consists of 3 fields of 4 bytes each.
		static const size_t kTagTableEntrySize = 12;

		if (icc_data == nullptr \|\| icc_size < sizeof(ICCHeader) + kICCIdentifierSize) {
		return ULTRAHDR_COLORGAMUT_UNSPECIFIED;
		}

		if (memcmp(icc_data, kICCIdentifier, sizeof(kICCIdentifier)) != 0) {
		return ULTRAHDR_COLORGAMUT_UNSPECIFIED;
		}

		uint8_t* icc_bytes = reinterpret_cast<uint8_t*>(icc_data) + kICCIdentifierSize;

		ICCHeader* header = reinterpret_cast<ICCHeader*>(icc_bytes);

		// Use 0 to indicate not found, since offsets are always relative to start
		// of ICC data and therefore a tag offset of zero would never be valid.
		size_t red_primary_offset = 0, green_primary_offset = 0, blue_primary_offset = 0;
		size_t red_primary_size = 0, green_primary_size = 0, blue_primary_size = 0;
		for (size_t tag_idx = 0; tag_idx < Endian_SwapBE32(header->tag_count); ++tag_idx) {
		uint32_t* tag_entry_start = reinterpret_cast<uint32_t*>(
		icc_bytes + sizeof(ICCHeader) + tag_idx * kTagTableEntrySize);
		// first 4 bytes are the tag signature, next 4 bytes are the tag offset,
		// last 4 bytes are the tag length in bytes.
		if (red_primary_offset == 0 && *tag_entry_start == Endian_SwapBE32(kTAG_rXYZ)) {
		red_primary_offset = Endian_SwapBE32(*(tag_entry_start+1));
		red_primary_size = Endian_SwapBE32(*(tag_entry_start+2));
		} else if (green_primary_offset == 0 && *tag_entry_start == Endian_SwapBE32(kTAG_gXYZ)) {
		green_primary_offset = Endian_SwapBE32(*(tag_entry_start+1));
		green_primary_size = Endian_SwapBE32(*(tag_entry_start+2));
		} else if (blue_primary_offset == 0 && *tag_entry_start == Endian_SwapBE32(kTAG_bXYZ)) {
		blue_primary_offset = Endian_SwapBE32(*(tag_entry_start+1));
		blue_primary_size = Endian_SwapBE32(*(tag_entry_start+2));
		}
		}

		if (red_primary_offset == 0 \|\| red_primary_size != kColorantTagSize \|\|
		kICCIdentifierSize + red_primary_offset + red_primary_size > icc_size \|\|
		green_primary_offset == 0 \|\| green_primary_size != kColorantTagSize \|\|
		kICCIdentifierSize + green_primary_offset + green_primary_size > icc_size \|\|
		blue_primary_offset == 0 \|\| blue_primary_size != kColorantTagSize \|\|
		kICCIdentifierSize + blue_primary_offset + blue_primary_size > icc_size) {
		return ULTRAHDR_COLORGAMUT_UNSPECIFIED;
		}

		uint8_t* red_tag = icc_bytes + red_primary_offset;
		uint8_t* green_tag = icc_bytes + green_primary_offset;
		uint8_t* blue_tag = icc_bytes + blue_primary_offset;

		// Serialize tags as we do on encode and compare what we find to that to
		// determine the gamut (since we don't have a need yet for full deserialize).
		if (tagsEqualToMatrix(kSRGB, red_tag, green_tag, blue_tag)) {
		return ULTRAHDR_COLORGAMUT_BT709;
		} else if (tagsEqualToMatrix(kDisplayP3, red_tag, green_tag, blue_tag)) {
		return ULTRAHDR_COLORGAMUT_P3;
		} else if (tagsEqualToMatrix(kRec2020, red_tag, green_tag, blue_tag)) {
		return ULTRAHDR_COLORGAMUT_BT2100;
		}

		// Didn't find a match to one of the profiles we write; indicate the gamut
		// is unspecified since we don't understand it.
		return ULTRAHDR_COLORGAMUT_UNSPECIFIED;
		}

		} // namespace android::ultrahdr

libs/ultrahdr/include/ultrahdr/gainmapmath.h

+57 −8

Original line number	Diff line number	Diff line
		@@ -218,24 +218,30 @@ struct ShepardsIDW {
		// except for those concerning transfer functions.

		/*
		* Calculate the luminance of a linear RGB sRGB pixel, according to IEC 61966-2-1.
		* Calculate the luminance of a linear RGB sRGB pixel, according to
		* IEC 61966-2-1/Amd 1:2003.
		*
		* [0.0, 1.0] range in and out.
		*/
		float srgbLuminance(Color e);

		/*
		* Convert from OETF'd srgb YUV to RGB, according to ECMA TR/98.
		* Convert from OETF'd srgb RGB to YUV, according to ITU-R BT.709-6.
		*
		* BT.709 YUV<->RGB matrix is used to match expectations for DataSpace.
		*/
		Color srgbYuvToRgb(Color e_gamma);
		Color srgbRgbToYuv(Color e_gamma);


		/*
		* Convert from OETF'd srgb RGB to YUV, according to ECMA TR/98.
		* Convert from OETF'd srgb YUV to RGB, according to ITU-R BT.709-6.
		*
		* BT.709 YUV<->RGB matrix is used to match expectations for DataSpace.
		*/
		Color srgbRgbToYuv(Color e_gamma);
		Color srgbYuvToRgb(Color e_gamma);

		/*
		* Convert from srgb to linear, according to IEC 61966-2-1.
		* Convert from srgb to linear, according to IEC 61966-2-1/Amd 1:2003.
		*
		* [0.0, 1.0] range in and out.
		*/
		@@ -257,6 +263,20 @@ constexpr size_t kSrgbInvOETFNumEntries = 1 << kSrgbInvOETFPrecision;
		*/
		float p3Luminance(Color e);

		/*
		* Convert from OETF'd P3 RGB to YUV, according to ITU-R BT.601-7.
		*
		* BT.601 YUV<->RGB matrix is used to match expectations for DataSpace.
		*/
		Color p3RgbToYuv(Color e_gamma);

		/*
		* Convert from OETF'd P3 YUV to RGB, according to ITU-R BT.601-7.
		*
		* BT.601 YUV<->RGB matrix is used to match expectations for DataSpace.
		*/
		Color p3YuvToRgb(Color e_gamma);


		////////////////////////////////////////////////////////////////////////////////
		// BT.2100 transformations - according to ITU-R BT.2100-2
		@@ -269,12 +289,16 @@ float p3Luminance(Color e);
		float bt2100Luminance(Color e);

		/*
		* Convert from OETF'd BT.2100 RGB to YUV.
		* Convert from OETF'd BT.2100 RGB to YUV, according to ITU-R BT.2100-2.
		*
		* BT.2100 YUV<->RGB matrix is used to match expectations for DataSpace.
		*/
		Color bt2100RgbToYuv(Color e_gamma);

		/*
		* Convert from OETF'd BT.2100 YUV to RGB.
		* Convert from OETF'd BT.2100 YUV to RGB, according to ITU-R BT.2100-2.
		*
		* BT.2100 YUV<->RGB matrix is used to match expectations for DataSpace.
		*/
		Color bt2100YuvToRgb(Color e_gamma);

		@@ -358,6 +382,31 @@ inline Color identityConversion(Color e) { return e; }
		*/
		ColorTransformFn getHdrConversionFn(ultrahdr_color_gamut sdr_gamut, ultrahdr_color_gamut hdr_gamut);

		/*
		* Convert between YUV encodings, according to ITU-R BT.709-6, ITU-R BT.601-7, and ITU-R BT.2100-2.
		*
		* Bt.709 and Bt.2100 have well-defined YUV encodings; Display-P3's is less well defined, but is
		* treated as Bt.601 by DataSpace, hence we do the same.
		*/
		Color yuv709To601(Color e_gamma);
		Color yuv709To2100(Color e_gamma);
		Color yuv601To709(Color e_gamma);
		Color yuv601To2100(Color e_gamma);
		Color yuv2100To709(Color e_gamma);
		Color yuv2100To601(Color e_gamma);

		/*
		* Performs a transformation at the chroma x and y coordinates provided on a YUV420 image.
		*
		* Apply the transformation by determining transformed YUV for each of the 4 Y + 1 UV; each Y gets
		* this result, and UV gets the averaged result.
		*
		* x_chroma and y_chroma should be less than or equal to half the image's width and height
		* respecitively, since input is 4:2:0 subsampled.
		*/
		void transformYuv420(jr_uncompressed_ptr image, size_t x_chroma, size_t y_chroma,
		ColorTransformFn fn);


		////////////////////////////////////////////////////////////////////////////////
		// Gain map calculations

libs/ultrahdr/include/ultrahdr/icc.h

+23 −2

Original line number	Diff line number	Diff line
		@@ -56,12 +56,16 @@ enum {
		Signature_XYZ = 0x58595A20,
		};


		typedef uint32_t FourByteTag;
		static inline constexpr FourByteTag SetFourByteTag(char a, char b, char c, char d) {
		return (((uint32_t)a << 24) \| ((uint32_t)b << 16) \| ((uint32_t)c << 8) \| (uint32_t)d);
		}

		static constexpr char kICCIdentifier[] = "ICC_PROFILE";
		// 12 for the actual identifier, +2 for the chunk count and chunk index which
		// will always follow.
		static constexpr size_t kICCIdentifierSize = 14;

		// This is equal to the header size according to the ICC specification (128)
		// plus the size of the tag count (4). We include the tag count since we
		// always require it to be present anyway.
		@@ -70,6 +74,10 @@ static constexpr size_t kICCHeaderSize = 132;
		// Contains a signature (4), offset (4), and size (4).
		static constexpr size_t kICCTagTableEntrySize = 12;

		// size should be 20; 4 bytes for type descriptor, 4 bytes reserved, 12
		// bytes for a single XYZ number type (4 bytes per coordinate).
		static constexpr size_t kColorantTagSize = 20;

		static constexpr uint32_t kDisplay_Profile = SetFourByteTag('m', 'n', 't', 'r');
		static constexpr uint32_t kRGB_ColorSpace = SetFourByteTag('R', 'G', 'B', ' ');
		static constexpr uint32_t kXYZ_PCSSpace = SetFourByteTag('X', 'Y', 'Z', ' ');
		@@ -225,9 +233,22 @@ private:
		static void compute_lut_entry(const Matrix3x3& src_to_XYZD50, float rgb[3]);
		static sp<DataStruct> write_clut(const uint8_t* grid_points, const uint8_t* grid_16);

		// Checks if a set of xyz tags is equivalent to a 3x3 Matrix. Each input
		// tag buffer assumed to be at least kColorantTagSize in size.
		static bool tagsEqualToMatrix(const Matrix3x3& matrix,
		const uint8_t* red_tag,
		const uint8_t* green_tag,
		const uint8_t* blue_tag);

		public:
		// Output includes JPEG embedding identifier and chunk information, but not
		// APPx information.
		static sp<DataStruct> writeIccProfile(const ultrahdr_transfer_function tf,
		const ultrahdr_color_gamut gamut);
		// NOTE: this function is not robust; it can infer gamuts that IccHelper
		// writes out but should not be considered a reference implementation for
		// robust parsing of ICC profiles or their gamuts.
		static ultrahdr_color_gamut readIccColorGamut(void* icc_data, size_t icc_size);
		};
		} // namespace android::ultrahdr

libs/ultrahdr/include/ultrahdr/jpegdecoderhelper.h

+9 −6

Original line number	Diff line number	Diff line
		@@ -83,11 +83,14 @@ public:
		*/
		size_t getEXIFSize();
		/*
		* Returns the position offset of EXIF package
		* (4 bypes offset to FF sign, the byte after FF E1 XX XX <this byte>),
		* or -1 if no EXIF exists.
		* Returns the ICC data from the image.
		*/
		int getEXIFPos() { return mExifPos; }
		void* getICCPtr();
		/*
		* Returns the decompressed ICC buffer size. This method must be called only after
		* calling decompressImage() or getCompressedImageParameters().
		*/
		size_t getICCSize();
		/*
		* Decompresses metadata of the image. All vectors are owned by the caller.
		*/
		@@ -112,12 +115,12 @@ private:
		std::vector<JOCTET> mXMPBuffer;
		// The buffer that holds EXIF Data.
		std::vector<JOCTET> mEXIFBuffer;
		// The buffer that holds ICC Data.
		std::vector<JOCTET> mICCBuffer;

		// Resolution of the decompressed image.
		size_t mWidth;
		size_t mHeight;
		// Position of EXIF package, default value is -1 which means no EXIF package appears.
		size_t mExifPos;
		};
		} /* namespace android::ultrahdr */