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/*
* Copyright 2009 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// package com.google.zxing.common;
// import com.google.zxing.Binarizer;
// import com.google.zxing.LuminanceSource;
// import com.google.zxing.NotFoundException;
use std::borrow::Cow;
use once_cell::sync::OnceCell;
use crate::common::Result;
use crate::{Binarizer, Exceptions, LuminanceSource};
use super::{BitArray, BitMatrix, LineOrientation};
const LUMINANCE_BITS: usize = 5;
const LUMINANCE_SHIFT: usize = 8 - LUMINANCE_BITS;
const LUMINANCE_BUCKETS: usize = 1 << LUMINANCE_BITS;
/**
* This Binarizer implementation uses the old ZXing global histogram approach. It is suitable
* for low-end mobile devices which don't have enough CPU or memory to use a local thresholding
* algorithm. However, because it picks a global black point, it cannot handle difficult shadows
* and gradients.
*
* Faster mobile devices and all desktop applications should probably use HybridBinarizer instead.
*
* @author dswitkin@google.com (Daniel Switkin)
* @author Sean Owen
*/
pub struct GlobalHistogramBinarizer<LS: LuminanceSource> {
//_luminances: Vec<u8>,
width: usize,
height: usize,
source: LS,
black_matrix: OnceCell<BitMatrix>,
black_row_cache: Vec<OnceCell<BitArray>>,
black_column_cache: Vec<OnceCell<BitArray>>,
}
impl<LS: LuminanceSource> Binarizer for GlobalHistogramBinarizer<LS> {
type Source = LS;
fn get_luminance_source(&self) -> &Self::Source {
&self.source
}
// Applies simple sharpening to the row data to improve performance of the 1D Readers.
fn get_black_row(&'_ self, y: usize) -> Result<Cow<'_, BitArray>> {
let row = self.black_row_cache[y].get_or_try_init(|| {
let source = self.get_luminance_source();
let width = source.get_width();
let mut row = BitArray::with_size(width);
// self.initArrays(width);
let localLuminances = source
.get_row(y)
.ok_or(Exceptions::index_out_of_bounds_with("row out of bounds"))?;
let mut localBuckets = [0; LUMINANCE_BUCKETS]; //self.buckets.clone();
for x in 0..width {
// for (int x = 0; x < width; x++) {
localBuckets[((localLuminances[x]) >> LUMINANCE_SHIFT) as usize] += 1;
}
let blackPoint = Self::estimateBlackPoint(&localBuckets)?;
if width < 3 {
// Special case for very small images
for (x, &lum) in localLuminances.iter().enumerate().take(width) {
// for x in 0..width {
// for (int x = 0; x < width; x++) {
if (lum as u32) < blackPoint {
row.set(x);
}
}
} else {
let mut left = localLuminances[0]; // & 0xff;
let mut center = localLuminances[1]; // & 0xff;
for x in 1..width - 1 {
// for (int x = 1; x < width - 1; x++) {
let right = localLuminances[x + 1];
// A simple -1 4 -1 box filter with a weight of 2.
if ((center as i64 * 4) - left as i64 - right as i64) / 2 < blackPoint as i64 {
row.set(x);
}
left = center;
center = right;
}
}
Ok(row)
})?;
Ok(Cow::Borrowed(row))
}
fn get_black_line(&'_ self, l: usize, lt: LineOrientation) -> Result<Cow<'_, BitArray>> {
if lt == LineOrientation::Row {
self.get_black_row(l)
} else {
let col = self.black_column_cache[l].get_or_try_init(|| {
let source = self.get_luminance_source();
let width = source.get_height();
let mut col = BitArray::with_size(width);
// self.initArrays(width);
let localLuminances = source.get_column(l);
let mut localBuckets = [0; LUMINANCE_BUCKETS]; //self.buckets.clone();
for x in 0..width {
// for (int x = 0; x < width; x++) {
localBuckets[((localLuminances[x]) >> LUMINANCE_SHIFT) as usize] += 1;
}
let blackPoint = Self::estimateBlackPoint(&localBuckets)?;
if width < 3 {
// Special case for very small images
for (x, lum) in localLuminances.iter().enumerate().take(width) {
// for x in 0..width {
// for (int x = 0; x < width; x++) {
if (*lum as u32) < blackPoint {
col.set(x);
}
}
} else {
let mut left = localLuminances[0]; // & 0xff;
let mut center = localLuminances[1]; // & 0xff;
for x in 1..width - 1 {
// for (int x = 1; x < width - 1; x++) {
let right = localLuminances[x + 1];
// A simple -1 4 -1 box filter with a weight of 2.
if ((center as i64 * 4) - left as i64 - right as i64) / 2
< blackPoint as i64
{
col.set(x);
}
left = center;
center = right;
}
}
Ok(col)
})?;
Ok(Cow::Borrowed(col))
}
}
// Does not sharpen the data, as this call is intended to only be used by 2D Readers.
fn get_black_matrix(&self) -> Result<&BitMatrix> {
let matrix = self
.black_matrix
.get_or_try_init(|| Self::build_black_matrix(&self.source))?;
Ok(matrix)
}
fn create_binarizer(&self, source: LS) -> Self {
Self::new(source)
}
fn get_width(&self) -> usize {
self.width
}
fn get_height(&self) -> usize {
self.height
}
fn get_black_row_from_matrix(&'_ self, y: usize) -> Result<Cow<'_, BitArray>> {
if let Some(matrix) = self.black_matrix.get() {
Ok(Cow::Owned(matrix.getRow(y as u32)))
} else {
self.get_black_row(y)
}
}
}
impl<LS: LuminanceSource> GlobalHistogramBinarizer<LS> {
// const EMPTY: [u8; 0] = [0; 0];
pub fn new(source: LS) -> Self {
Self {
//_luminances: vec![0; source.getWidth()],
width: source.get_width(),
height: source.get_height(),
black_matrix: OnceCell::new(),
black_row_cache: vec![OnceCell::default(); source.get_height()],
black_column_cache: vec![OnceCell::default(); source.get_width()],
source,
}
}
fn build_black_matrix(source: &LS) -> Result<BitMatrix> {
// let source = source.getLuminanceSource();
let width = source.get_width();
let height = source.get_height();
let mut matrix = BitMatrix::new(width as u32, height as u32)?;
// Quickly calculates the histogram by sampling four rows from the image. This proved to be
// more robust on the blackbox tests than sampling a diagonal as we used to do.
// self.initArrays(width);
let mut localBuckets = [0; LUMINANCE_BUCKETS]; //self.buckets.clone();
for y in 1..5 {
// for (int y = 1; y < 5; y++) {
let row = height * y / 5;
let localLuminances = source
.get_row(row)
.ok_or(Exceptions::index_out_of_bounds_with("row out of bounds"))?;
let right = (width * 4) / 5;
for pixel in &localLuminances[(width / 5)..right] {
// for x in (width / 5)..right {
// let pixel = localLuminances[x];
localBuckets[(pixel >> LUMINANCE_SHIFT) as usize] += 1;
}
}
let blackPoint = Self::estimateBlackPoint(&localBuckets)?;
// We delay reading the entire image luminance until the black point estimation succeeds.
// Although we end up reading four rows twice, it is consistent with our motto of
// "fail quickly" which is necessary for continuous scanning.
let localLuminances = source.get_matrix();
for y in 0..height {
let offset = y * width;
for x in 0..width {
let pixel = localLuminances[offset + x];
if (pixel as u32) < blackPoint {
matrix.set(x as u32, y as u32);
}
}
}
Ok(matrix)
}
fn estimateBlackPoint<const BUCKET_COUNT: usize>(buckets: &[u32; BUCKET_COUNT]) -> Result<u32> {
// Find the tallest peak in the histogram.
let mut maxBucketCount = 0;
let mut firstPeak = 0;
let mut firstPeakSize = 0;
for (x, &bucket) in buckets.iter().enumerate() {
if bucket > firstPeakSize {
firstPeak = x;
firstPeakSize = bucket;
}
if bucket > maxBucketCount {
maxBucketCount = bucket;
}
}
// Find the second-tallest peak which is somewhat far from the tallest peak.
let mut secondPeak = 0;
let mut secondPeakScore = 0;
for (x, bucket) in buckets.iter().enumerate() {
let distanceToBiggest = (x as i32 - firstPeak as i32).unsigned_abs();
// Encourage more distant second peaks by multiplying by square of distance.
let score = *bucket * distanceToBiggest * distanceToBiggest;
if score > secondPeakScore {
secondPeak = x;
secondPeakScore = score;
}
}
// Make sure firstPeak corresponds to the black peak.
if firstPeak > secondPeak {
std::mem::swap(&mut firstPeak, &mut secondPeak);
}
// If there is too little contrast in the image to pick a meaningful black point, throw rather
// than waste time trying to decode the image, and risk false positives.
if secondPeak - firstPeak <= BUCKET_COUNT / 16 {
return Err(Exceptions::not_found_with(
"secondPeak - firstPeak <= numBuckets / 16 ",
));
}
// Find a valley between them that is low and closer to the white peak.
let mut bestValley = secondPeak as isize - 1;
let mut bestValleyScore = -1;
let mut x = secondPeak as isize;
while x > firstPeak as isize {
let fromFirst = x - firstPeak as isize;
let score = fromFirst
* fromFirst
* (secondPeak as isize - x)
* (maxBucketCount - buckets[x as usize]) as isize;
if score as i32 > bestValleyScore {
bestValley = x;
bestValleyScore = score as i32;
}
x -= 1;
}
Ok((bestValley as u32) << LUMINANCE_SHIFT)
}
}