Allow line images with larger width (depending on height)

Training with normalized line images higher than 36 px also results in larger widths.
The limit should therefore depend on the height used for the normalization.

Signed-off-by: Stefan Weil <sw@weilnetz.de>

src/lstm/lstmrecognizer.cpp

@@ -233,8 +233,6 @@ bool LSTMRecognizer::RecognizeLine(const ImageData& image_data, bool invert,
                                    bool debug, bool re_invert, bool upside_down,
                                    float* scale_factor, NetworkIO* inputs,
                                    NetworkIO* outputs) {
-  // Maximum width of image to train on.
-  const int kMaxImageWidth = 4096;
   // This ensures consistent recognition results.
   SetRandomSeed();
   int min_width = network_->XScaleFactor();
@@ -244,6 +242,8 @@ bool LSTMRecognizer::RecognizeLine(const ImageData& image_data, bool invert,
     tprintf("Line cannot be recognized!!\n");
     return false;
   }
+  // Maximum width of image to train on.
+  const int kMaxImageWidth = 128 * pixGetHeight(pix);
   if (network_->IsTraining() && pixGetWidth(pix) > kMaxImageWidth) {
     tprintf("Image too large to learn!! Size = %dx%d\n", pixGetWidth(pix),
             pixGetHeight(pix));