Ref<BitArray> GlobalHistogramBinarizer::getBlackRow(int y, Ref<BitArray> row) {
if (y == cached_row_num_) {
- return cached_row_;
+ if (cached_row_ != NULL) {
+ return cached_row_;
+ } else {
+ throw IllegalArgumentException("Too little dynamic range in luminance");
+ }
}
vector<int> histogram(LUMINANCE_BUCKETS, 0);