more ICC tags support

Author: lvandeve

lodepng_util.cpp

@@ -285,7 +285,7 @@ struct LodePNGICC {
 
   // Parameters of a tone reproduction curve, either with a power law formulaa or with a lookup table.
   struct Curve {
-    int type; // 0=linear, 1=lut, 2 = simple gamma, 3-6 = parametric (matches ICC parametric types 1-4)
+    unsigned type; // 0=linear, 1=lut, 2 = simple gamma, 3-6 = parametric (matches ICC parametric types 1-4)
     std::vector<float> lut; // for type 1
     float gamma; // for type 2 and more
     float a, b, c, d, e, f; // for type 3-7
@@ -419,7 +419,9 @@ static unsigned parseICC(LodePNGICC* icc, const unsigned char* data, size_t size
     pos += 4;
     size_t offset = decodeICCUint32(data, size, &pos);
     unsigned tagsize = decodeICCUint32(data, size, &pos);
-    if(pos >= size || offset + tagsize > size) return 1;
+    if(pos >= size || offset >= size) return 1;
+    if(offset + tagsize > size) return 1;
+    if(tagsize < 8) return 1;
 
     if(isICCword(data, size, namepos, "wtpt")) {
       offset += 8; // skip tag and reserved
@@ -455,12 +457,12 @@ static unsigned parseICC(LodePNGICC* icc, const unsigned char* data, size_t size
               isICCword(data, size, namepos, "gTRC") ||
               isICCword(data, size, namepos, "bTRC") ||
               isICCword(data, size, namepos, "kTRC")) {
+      char c = (char)data[namepos];
+      int channel = (c == 'b') ? 2 : (c == 'g' ? 1 : 0);
+      // "curv": linear, gamma power or LUT
       if(isICCword(data, size, offset, "curv")) {
         icc->has_trc = true;
-        char c = (char)data[namepos];
-        int channel = (c == 'b') ? 2 : (c == 'g' ? 1 : 0);
         LodePNGICC::Curve* trc = &icc->trc[channel];
-        // TODO: set type to other things if it's not LUT
         offset += 8; // skip tag "curv" and reserved
         size_t count = decodeICCUint32(data, size, &offset);
         if(count == 0) {
@@ -477,7 +479,37 @@ static unsigned parseICC(LodePNGICC* icc, const unsigned char* data, size_t size
           }
         }
       }
+      // "para": parametric formula with gamma power, multipliers, biases and comparison point
+      // TODO: test this on a realistic sample
+      if(isICCword(data, size, offset, "para")) {
+        icc->has_trc = true;
+        LodePNGICC::Curve* trc = &icc->trc[channel];
+        offset += 8; // skip tag "para" and reserved
+        unsigned type = decodeICCUint16(data, size, &offset);
+        offset += 2;
+        if(type > 4) return 1; // unknown parametric curve type
+        trc->type = type + 2;
+        trc->gamma = decodeICC15Fixed16(data, size, &offset);
+        if(type >= 1) {
+          trc->a = decodeICC15Fixed16(data, size, &offset);
+          trc->b = decodeICC15Fixed16(data, size, &offset);
+        }
+        if(type >= 2) {
+          trc->c = decodeICC15Fixed16(data, size, &offset);
+        }
+        if(type >= 3) {
+          trc->d = decodeICC15Fixed16(data, size, &offset);
+        }
+        if(type == 4) {
+          trc->e = decodeICC15Fixed16(data, size, &offset);
+          trc->f = decodeICC15Fixed16(data, size, &offset);
+        }
+      }
+      // TODO: verify: does the "chrm" tag participate in computation so should be parsed?
     }
+    // Return error if any parse went beyond the filesize. Note that the
+    // parsing itself was always safe since it bound-checks inside.
+    if(offset > size) return 1;
   }
 
   return 0;

pngdetail.cpp

@@ -916,10 +916,16 @@ static int getICCInt32(const unsigned char* icc, size_t size, size_t pos) {
   return (int)((icc[pos] << 24) | (icc[pos + 1] << 16) | (icc[pos + 2] << 8) | (icc[pos + 3] << 0));
 }
 
+// Signed
 static float getICC15Fixed16(const unsigned char* icc, size_t size, size_t pos) {
   return getICCInt32(icc, size, pos) / 65536.0;
 }
 
+// Unsigned
+static float getICC16Fixed16(const unsigned char* icc, size_t size, size_t pos) {
+  return getICCUint32(icc, size, pos) / 65536.0;
+}
+
 static std::string printableICCWord(const unsigned char* icc, size_t size, size_t pos) {
   if (pos + 4 > size) {
     return "out of range";
@@ -961,7 +967,7 @@ void printICCDetails(const unsigned char* icc, size_t size, const std::string& i
          getICCUint16(icc, size, 24), getICCUint16(icc, size, 26), getICCUint16(icc, size, 28),
          getICCUint16(icc, size, 30), getICCUint16(icc, size, 32), getICCUint16(icc, size, 34));
   std::cout << indent << "signature: " << printableICCWord(icc, size, 36) << std::endl;
-  std::cout << indent << "target: " << printableICCWord(icc, size, 40) << std::endl;
+  std::cout << indent << "platform: " << printableICCWord(icc, size, 40) << std::endl;
   std::cout << indent << "flags: " << getICCUint32(icc, size, 44) << std::endl;
   std::cout << indent << "device manufacturer: " << printableICCWord(icc, size, 48) << ", ";
   std::cout << "device model: " << printableICCWord(icc, size, 52) << ", ";
@@ -1018,13 +1024,35 @@ void printICCDetails(const unsigned char* icc, size_t size, const std::string& i
       }
       if(lutsize == 0) std::cout << " (linear)";
     }
+    if(datatype == "para") {
+      unsigned type = getICCUint16(icc, size, offset + 8);
+      float gamma = getICC15Fixed16(icc, size, offset + 12);
+      int numparams = (type == 4) ? 7 : ((type >= 1 && type <= 3) ? (type + 1) : 0);
+      std::cout << " type: " << type << ", gamma: " <<  gamma;
+      if(numparams > 0) {
+        std::cout << "params: ";
+        for(int j = 0; j < numparams; j++) {
+          if(j > 0) std::cout << ", ";
+          std::cout << getICC15Fixed16(icc, size, offset + 16 + j * 4);
+        }
+      }
+    }
     if(datatype == "sf32") {
       std::cout << ":";
       for(size_t j = 8; j < tagsize; j += 4) {
         float v = getICC15Fixed16(icc, size, offset + j);
         std::cout << " " << v;
       }
     }
+    if(datatype == "chrm") {
+      size_t numchannels = getICCUint16(icc, size, offset + 8);
+      std::cout << ": n:" << numchannels
+                << " phosphor:" << getICCUint16(icc, size, offset + 10);
+      for(size_t j = 0; j < numchannels; j++) {
+        std::cout << " xy:" << getICC16Fixed16(icc, size, offset + 12 + j * 8)
+                  << "," << getICC16Fixed16(icc, size, offset + 12 + j * 8 + 4);
+      }
+    }
     if(datatype == "text" || datatype == "mluc" || datatype == "desc") {
       // TODO: this is a bit of a simplification of the parse for now, e.g.
       // ignoring UTF-16, instead implicitely skipping non-ASCII bytes, and