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上传背景移除算法

This commit is contained in:
masayume 2022-02-14 10:49:07 +08:00
parent 1e8d06e002
commit b3afcc4382
2 changed files with 214 additions and 0 deletions
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150
huagao/ImageProcess/ImageApplyFadeBackGroundColor.cpp Normal file
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#include "ImageApplyFadeBackGroundColor.h"
CImageApplyFadeBackGroudColor::CImageApplyFadeBackGroudColor(int threshold, int offset, int range)
: m_threshold(threshold)
, m_offset(offset)
, m_range(range)
{
memset(m_table1, 255, 768);
memset(m_table1, 0, m_threshold * 3);
memset(m_table2, 255, 256 * 3);
for (size_t i = 0; i < 256; i++)
m_table2[i] = i;
}
CImageApplyFadeBackGroudColor::~CImageApplyFadeBackGroudColor()
{
}
void CImageApplyFadeBackGroudColor::apply(cv::Mat& pDib, int side)
{
if (pDib.channels() != 3)
return;
#if 0
cv::Mat mask;
cv::cvtColor(pDib, mask, cv::COLOR_BGR2GRAY);
cv::threshold(mask, mask, m_threshold, 255, cv::THRESH_BINARY);
//cv::imwrite("mask.jpg", mask);
cv::Mat bgr[3];
cv::split(pDib, bgr);
int histSize = 255;
float range[] = { 0, 255 };
const float* histRange = { range };
cv::Mat hist_bgr[3];
cv::Scalar mean_bgr;
for (size_t i = 0; i < 3; i++)
{
cv::calcHist(&bgr[i], 1, 0, mask, hist_bgr[i], 1, &histSize, &histRange);
double maxVal = 0;
cv::Point maxLoc;
cv::minMaxLoc(hist_bgr[i], NULL, &maxVal, NULL, &maxLoc);
mean_bgr[i] = maxLoc.y;
}
cv::add(pDib, cv::Scalar::all(255 + m_offset) - mean_bgr, pDib, mask);
#else
fadeBackground(pDib.data, pDib.step, pDib.rows, m_threshold, m_offset, m_range);
#endif
}
void CImageApplyFadeBackGroudColor::fadeBackground(unsigned char* data, int bytesPerLine, int height, int threshold, int offset, int range)
{
int hist_bgr[3][256] = { 0 };
int width = bytesPerLine / 3;
unsigned char* mask = new unsigned char[width * height];
unsigned char* ptr_data = data;
unsigned char* ptr_mask = mask;
//创建掩模mask，并且统计三通道的直方图
for (size_t i = 0; i < height; i++)
{
int x = 0;
unsigned char b = 0;
for (size_t j = 0; j < width; j++)
{
b = m_table1[ptr_data[x] + ptr_data[x + 1] + ptr_data[x + 2]];
ptr_mask[j] = b;
for (size_t k = 0; k < 3; k++)
hist_bgr[k][ptr_data[x + k] & b]++;
x += 3;
}
ptr_data += bytesPerLine;
ptr_mask += width;
}
//统计背景色
int max_vals[3] = { 0 };
int max_indexes[3];
for (size_t i = 1; i < 256; i++)
for (size_t j = 0; j < 3; j++)
if (hist_bgr[j][i] > max_vals[j])
{
max_vals[j] = hist_bgr[j][i];
max_indexes[j] = i;
}
//创建背景色误查值表，在误差±range范围内的颜色被同样视为背景色
for (size_t i = 0; i < 3; i++)
{
memset(m_table_rgb[i], 0, 256);
int start = cv::max(max_indexes[i] - range, 0);
int end = cv::min(max_indexes[i] + range, 255);
memset(m_table_rgb[i] + start, 255, end - start + 1);
}
//根据背景色误差查值表，更新掩模，排除背景色以外的内容
ptr_data = data;
ptr_mask = mask;
for (size_t i = 0; i < height; i++)
{
int x = 0;
for (size_t j = 0; j < width; j++)
{
ptr_mask[j] &= m_table_rgb[0][ptr_data[x]] & m_table_rgb[1][ptr_data[x + 1]] & m_table_rgb[2][ptr_data[x + 2]];
x += 3;
}
ptr_data += bytesPerLine;
ptr_mask += width;
}
//根据掩模，除背景色
unsigned char offset_rgb[3];
for (size_t i = 0; i < 3; i++)
offset_rgb[i] = 255 + offset - max_indexes[i];
ptr_data = data;
ptr_mask = mask;
for (size_t i = 0; i < height; i++)
{
int x = 0;
for (size_t j = 0; j < width; j++)
{
for (size_t k = 0; k < 3; k++)
ptr_data[x + k] = m_table2[(int)ptr_data[x + k] + (offset_rgb[k] & ptr_mask[j])];
x += 3;
}
ptr_data += bytesPerLine;
ptr_mask += width;
}
delete[] mask;
}
void CImageApplyFadeBackGroudColor::apply(std::vector<cv::Mat>& mats, bool isTwoSide)
{
(void)isTwoSide;
int i = 0;
for (cv::Mat& var : mats)
if (!var.empty())
{
apply(var, i);
i++;
}
}

64
huagao/ImageProcess/ImageApplyFadeBackGroundColor.h Normal file
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/*
* ====================================================
* 功能：消除文稿纸张底色
* 作者：刘丁维
* 生成时间：2020/11/30
* 最近修改时间：2021/04/14 v2.0 改为档位设置
* 2021/04/14 v2.1 调整方案，与LINUX方案保持一致。
* 2021/08/03 v2.2 自定义获取饱和度算法，避免不同opencv版本结果存在偏差。
* 2021/10/12 v2.3 重构算法，去除原来分档设定改为自动识别颜色，并去除底色。
* 2021/10/23 v3.0 重构算法。避开黑色背景（制作掩模），计算文稿平均底色，并进行增白。
* 2021/10/26 v3.1 构造函数增加参数，可设置生成掩模时的阈值。
* 2021/10/28 v3.2 重构算法，改用纯C++代码实现功能，提高处理速度。
* 2021/10/29 v3.3 优化算法，增加range参数。针对复杂内容的图像，能够有效甄别背景和非背景内容。
* 版本号：v3.2
* ====================================================
*/
#ifndef IMAGE_APPLY_FADE_BACKGROUND_COLOR_H
#define IMAGE_APPLY_FADE_BACKGROUND_COLOR_H
#include "ImageApply.h"
class CImageApplyAdjustColors;
class CImageApplyFadeBackGroudColor : public CImageApply
{
public:
/// <summary>
/// 构造函数
/// </summary>
/// <param name="offset">在自动识别增白参数的基础上，增加的偏移量。取值范围[-255, 255]</param>
CImageApplyFadeBackGroudColor(int threshold = 100, int offset = 0, int range = 40);
virtual ~CImageApplyFadeBackGroudColor();
virtual void apply(cv::Mat& pDib, int side);
virtual void apply(std::vector<cv::Mat>& mats, bool isTwoSide);
private:
/// <summary>
/// 除文稿底色算法，仅支持24位图像
/// </summary>
/// <param name="data">图像数据头指针</param>
/// <param name="bytesPerLine">每行数据大小</param>
/// <param name="height">图像高度</param>
/// <param name="threshold">阈值，参考值为100</param>
/// <param name="offset">文稿底色增亮偏移量，默认为0。值越大，背景越白，反之越暗</param>
/// <param name="range">底色误差范围，色彩与识别到的底色误差在[-range, range]范围内，视为底色，否则不会被消除</param>
void fadeBackground(unsigned char* data, int bytesPerLine, int height, int threshold, int offset, int range);
private:
int m_threshold;
int m_offset;
int m_range;
uchar m_table1[768];
uchar m_table2[512];
uchar m_table_rgb[3][256];
};
#endif // !IMAGE_APPLY_FADE_BACKGROUND_COLOR_H