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c# - 查找图像内容并在其周围绘制矩形

转载 作者:行者123 更新时间:2023-11-30 23:13:16 25 4
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关于

我正在使用 WinForms。在我的表单中,我有一个 pictureboxpicturebox 大小模式设置为 zoom。我使用 picturebox 查看 TIF 图像。 TIF 图像是灰度图像(仅限黑白)。

我的应用能做什么

我的应用程序找到文档中的第一个黑色像素和最后一个黑色像素,并在其周围绘制一个红色矩形。希望它会在图像内容周围绘制矩形。

问题

有时,TIF 文档在图像内容周围有 Blob /圆点。这使我的应用程序关闭。它不知道图像内容的开始和结束位置。如果文档有 Blob /点,如何找到 TIF 文档的内容并在其周围绘制一个矩形?

关于文档

  • 仅黑白(1 位深度)
  • TIF 文件
  • 文档总是有字母和数字
  • 字母和数字总是比点/点大
  • 甚至在内容中也可以在整个图像上有多个 Blob
  • 背景总是白色
  • 内容总是黑色
  • Blob 也是黑色的

下载测试图片链接:

• 文件滴管: http://www.filedropper.com/test-tifs

• 快速分享: https://ufile.io/2qiir


我发现了什么

根据我的研究,我发现了 AForge.Imaging 库,它有许多可能帮助我实现目标的成像过滤器。我正在考虑使用中值过滤器去除 Blob /点或使用其他过滤器来获得所需的结果。

我尝试了什么

我尝试应用 AForge 库中的中值过滤器来去除 Blob ,但只去除了一些 Blob 。我不得不多次重复回复过滤器以去除大部分位置以找到内容,但仍然很难找到内容。这种方法对我来说不太奏效。

AForge 过滤器链接: http://www.aforgenet.com/framework/docs/html/cdf93487-0659-e371-fed9-3b216efb6954.htm


代码

    private void btn_Draw_Click(object sender, EventArgs e)
{
// Wrap the creation of the OpenFileDialog instance in a using statement,
// rather than manually calling the Dispose method to ensure proper disposal
using (OpenFileDialog dlg = new OpenFileDialog())
{
if (dlg.ShowDialog() == DialogResult.OK)
{
pictureBox1.Image = new Bitmap(dlg.FileName);

int xMax = pictureBox1.Image.Width;
int yMax = pictureBox1.Image.Height;

startX = Int32.MaxValue;
startY = Int32.MaxValue;
endX = Int32.MinValue;
endY = Int32.MinValue;


using (Bitmap bmp = new Bitmap(pictureBox1.Image))
{
for (var y = 0; y < yMax; y+=3)
{
for (var x = 0; x < xMax; x+=3)
{
Color col = bmp.GetPixel(x, y);
if(col.ToArgb() == Color.Black.ToArgb())
{
// Finds first black pixel
if (x < startX)
startX = x;
if(y < startY)
startY = y;

// Finds last black pixel
if (x > endX)
endX = x;
if (y > endY)
endY = y;
}
}
}


int picWidth = pictureBox1.Size.Width;
int picHeight = pictureBox1.Size.Height;


float imageRatio = xMax / (float)yMax; // image W:H ratio
float containerRatio = picWidth / (float)picHeight; // container W:H ratio

if (imageRatio >= containerRatio)
{
// horizontal image
float scaleFactor = picWidth / (float)xMax;
float scaledHeight = yMax * scaleFactor;
// calculate gap between top of container and top of image
float filler = Math.Abs(picHeight - scaledHeight) / 2;
//float filler = 0;

startX = (int)(startX * scaleFactor);
endX = (int)(endX * scaleFactor);
startY = (int)((startY) * scaleFactor + filler);
endY = (int)((endY) * scaleFactor + filler);
}
else
{
// vertical image
float scaleFactor = picHeight / (float)yMax;
float scaledWidth = xMax * scaleFactor;
float filler = Math.Abs(picWidth - scaledWidth) / 2;
startX = (int)((startX) * scaleFactor + filler);
endX = (int)((endX) * scaleFactor + filler);
startY = (int)(startY * scaleFactor);
endY = (int)(endY * scaleFactor);
}

//var scaleX = picWidth / (float)xMax;
//var scaleY = picHeight / (float)yMax;

//startX = (int)Math.Round(startX * scaleX);
//startY = (int)Math.Round(startY * scaleY);
//endX = (int)Math.Round(endX * scaleX);
//endY = (int)Math.Round(endY * scaleY);

}
}
}
}

private bool _once = true;
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (_once)
{
//Rectangle ee = new Rectangle(35, 183, 405, 157);
Rectangle ee = new Rectangle(startX, startY, endX - startX, endY - startY);
System.Diagnostics.Debug.WriteLine(startX + ", " + startY + ", " + (endX - startX) + ", " + (endY - startY));
using (Pen pen = new Pen(Color.Red, 2))
{
e.Graphics.DrawRectangle(pen, ee);
}
//_once = false;
}
}

内容周围没有任何 Blob 的 Tif 文档

enter image description here

内容周围有 Blob 的 Tif 文档 enter image description here

示例图片 1:


enter image description here

示例图片 2


enter image description here :

示例图片 3


enter image description here

最佳答案

以下实验似乎满足您的所有要求。

我将以下控件放在 Form1 上

一个 MenuStrip:Docking=Top,有 2 个 MenuItems - 第一个用于打开文件,第二个用于运行算法

一个进度条:Docking=Top,用来观察加载和算法的性能

Docking=Fill 和 AutoScroll=true 的面板

一张图片放入面板,Point(0,0),其余默认。 SizeMode=正常。

更新

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

// Opens an image file.
private void openToolStripMenuItem_Click(object sender, EventArgs e)
{
OpenFileDialog dlg = new OpenFileDialog();
if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
this.image = Image.FromFile(dlg.FileName) as Bitmap;
this.pictureBox1.Image = image;
this.pictureBox1.Invalidate();
}
}

Bitmap image;

// finds top, left, right and bottom bounds of the content in TIFF file.
//
private void findBoundsToolStripMenuItem_Click(object sender, EventArgs e)
{
int contentSize = 70;

this.left = 0;
this.top = 0;
this.right = this.pictureBox1.Width - 1;
this.bottom = this.pictureBox1.Height - 1;

int h = image.Height;
int w = image.Width;
this.progressBar1.Value = 0;
this.progressBar1.Maximum = 4;

for (int y = 0; y < h; y++)
{
for (int x = 0; x < w; x++)
{

if (this.image.GetPixel(x, y).ToArgb() == Black)
{
int size = this.image.GetBlackRegionSize(x, y);
if (this.image.GetBlackRegionSize(x, y) > contentSize)
{
this.top = y;
goto label10;
}
}

}
}

label10:
this.progressBar1.Increment(1);
for (int y = h - 1; y >= 0; y--)
{
for (int x = 0; x < w; x++)
{

if (this.image.GetPixel(x, y).ToArgb() == Black)
{
if (this.image.GetBlackRegionSize(x, y) > contentSize)
{
this.bottom = y;
goto label11;
}
}
}
}

label11:
this.progressBar1.Increment(1);
for (int x = 0; x < w; x++)
{
for (int y = 0; y < h; y++)
{

if (this.image.GetPixel(x, y).ToArgb() == Black)
{
if (this.image.GetBlackRegionSize(x, y) > contentSize)
{
this.left = x;
goto label12;
}
}
}
}

label12:
this.progressBar1.Increment(1);
for (int x = w - 1; x >= 0; x--)
{
for (int y = 0; y < h; y++)
{

if (this.image.GetPixel(x, y).ToArgb() == Black)
{
if (this.image.GetBlackRegionSize(x, y) > contentSize)
{
this.right = x;
goto label13;
}
}
}
}

label13:
this.progressBar1.Increment(1);

this.pictureBox1.Invalidate();
}

internal static readonly int Black = Color.Black.ToArgb();
internal static readonly int White = Color.White.ToArgb();

int top;
int bottom;
int left;
int right;

private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (pictureBox1.Image == null)
{
return;
}

int xMax = pictureBox1.Image.Width;
int yMax = pictureBox1.Image.Height;

int startX = this.left;
int startY = this.top;
int endX = this.right;
int endY = this.bottom;


int picWidth = pictureBox1.Size.Width;
int picHeight = pictureBox1.Size.Height;


float imageRatio = xMax / (float)yMax; // image W:H ratio
float containerRatio = picWidth / (float)picHeight; // container W:H ratio

if (imageRatio >= containerRatio)
{
// horizontal image
float scaleFactor = picWidth / (float)xMax;
float scaledHeight = yMax * scaleFactor;
// calculate gap between top of container and top of image
float filler = Math.Abs(picHeight - scaledHeight) / 2;
//float filler = 0;

startX = (int)(startX * scaleFactor);
endX = (int)(endX * scaleFactor);
startY = (int)((startY) * scaleFactor + filler);
endY = (int)((endY) * scaleFactor + filler);
}
else
{
// vertical image
float scaleFactor = picHeight / (float)yMax;
float scaledWidth = xMax * scaleFactor;
float filler = Math.Abs(picWidth - scaledWidth) / 2;
startX = (int)((startX) * scaleFactor + filler);
endX = (int)((endX) * scaleFactor + filler);
startY = (int)(startY * scaleFactor);
endY = (int)(endY * scaleFactor);
}

//if (_once)
//Rectangle ee = new Rectangle(35, 183, 405, 157);
Rectangle ee = new Rectangle(startX, startY, endX - startX, endY - startY);
System.Diagnostics.Debug.WriteLine(startX + ", " + startY + ", " + (endX - startX) + ", " + (endY - startY));
using (Pen pen = new Pen(Color.Red, 2))
{
e.Graphics.DrawRectangle(pen, ee);
}
//_once = false;
}
}

static class BitmapHelper
{
internal static int GetBlackRegionSize(this Bitmap image, int x, int y)
{
int size = 0;
GetRegionSize(image, new List<Point>(), x, y, 0, ref size);
return size;
}

// this constant prevents StackOverFlow exception.
// also it has effect on performance.
// It's value must be greater than the value of contentSize defined in findBoundsToolStripMenuItem_Click(object sender, EventArgs e) method.
const int MAXLEVEL = 100;

static void GetRegionSize(this Bitmap image, List<Point> list, int x, int y, int level, ref int size)
{
if (x >= image.Width || x < 0 || y >= image.Height || y < 0 || list.Contains(x, y) || image.GetPixel(x, y).ToArgb() != Form1.Black || level > MAXLEVEL)
{
return;
}

if (size < level)
{
size = level;
}

list.Add(new Point(x, y));

image.GetRegionSize(list, x, y - 1, level + 1, ref size);
image.GetRegionSize(list, x, y + 1, level + 1, ref size);
image.GetRegionSize(list, x - 1, y, level + 1, ref size);
image.GetRegionSize(list, x + 1, y, level + 1, ref size);
}

static bool Contains(this List<Point> list, int x, int y)
{
foreach (Point point in list)
{
if (point.X == x && point.Y == y)
{
return true;
}
}
return false;
}
}

}

"this.pictureBox1.Size = image.Size;"已被删除。 Paint 事件处理程序的代码已更改。 PictureBox 大小模式现在可以设置为缩放。

Screenshot

更新 2

我试图简化代码并提高性能。

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication3
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.pictureBox1.Paint += new PaintEventHandler(this.pictureBox1_Paint);
}

// Opens an image file
// and runs "FindBounds()" method
private void openToolStripMenuItem_Click(object sender, EventArgs e)
{
OpenFileDialog dlg = new OpenFileDialog();
if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
this.image = Image.FromFile(dlg.FileName) as Bitmap;
FindBounds();
this.pictureBox1.Image = image;
this.pictureBox1.Invalidate();
}
}

Bitmap image;

// Possible maximum side of a spot or a dot in the image
int maxSpotOrDotSide = 7;

// Finds top, left, right and bottom bounds of the content in TIFF file.
private void FindBounds()
{
// Possible maximum area of a spot or a dot in the image
int maxSpotOrDotArea = maxSpotOrDotSide * maxSpotOrDotSide;

this.left = 0;
this.top = 0;
this.right = this.pictureBox1.Width - 1;
this.bottom = this.pictureBox1.Height - 1;

int h = image.Height;
int w = image.Width;
int num = w * h;

// Incrementers. I tested with greater values
// like "x = 2", "x = 5" and it increased performance.
// But we must be carefull as this may cause skipping content.
int dx = 1; // Incrementer for "x"
int dy = 1; // Incrementer for "y"

// Initialization of "progressBar1"
this.progressBar1.Value = 0;
this.progressBar1.Maximum = num;

// Content of the image
BlackContent imageContent = null;

// Here we will scan pixels of the image
// starting from top left corner and
// finishing at bottom right
for (int y = 0; y < h; y += dx)
{
for (int x = 0; x < w; x += dy)
{
int val = y * w + x;
this.progressBar1.Value = val > num ? num : val;
// This block skips scanning imageContent
// thus should increase performance.
if (imageContent != null && imageContent.Contains(x, y))
{
x = imageContent.Right;
continue;
}

// Interesting things begin to happen
// after we detect the first Black pixel
if (this.image.GetPixel(x, y).ToArgb() == Black)
{
BlackContent content = new BlackContent(x, y);
// Start Flood-Fill algorithm
content.FloodFill(this.image);
if (content.Area > maxSpotOrDotArea)
{
if (imageContent == null)
{
imageContent = content;
}
imageContent.Include(content.Right, content.Bottom);
imageContent.Include(content.Left, content.Top);
}
else
{
// Here it's better we increase values of the incrementers.
// Depending on size of spots/dots.
// It should increase performance.
if (dx < content.Width) dx = content.Width;
if (dy < content.Height) dy = content.Height;
}
}

}
}

// Everything is done.
this.progressBar1.Value = this.progressBar1.Maximum;

// If image content has been detected
// then we save the information
if (imageContent != null)
{
this.left = imageContent.Left;
this.top = imageContent.Top;
this.right = imageContent.Right;
this.bottom = imageContent.Bottom;
}

this.pictureBox1.Invalidate();
}

internal static readonly int Black = Color.Black.ToArgb();
internal static readonly int White = Color.White.ToArgb();

int top;
int bottom;
int left;
int right;

private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
if (pictureBox1.Image == null)
{
return;
}

int xMax = pictureBox1.Image.Width;
int yMax = pictureBox1.Image.Height;

int startX = this.left;
int startY = this.top;
int endX = this.right;
int endY = this.bottom;


int picWidth = pictureBox1.Size.Width;
int picHeight = pictureBox1.Size.Height;


float imageRatio = xMax / (float)yMax; // image W:H ratio
float containerRatio = picWidth / (float)picHeight; // container W:H ratio

if (imageRatio >= containerRatio)
{
// horizontal image
float scaleFactor = picWidth / (float)xMax;
float scaledHeight = yMax * scaleFactor;
// calculate gap between top of container and top of image
float filler = Math.Abs(picHeight - scaledHeight) / 2;
//float filler = 0;

startX = (int)(startX * scaleFactor);
endX = (int)(endX * scaleFactor);
startY = (int)((startY) * scaleFactor + filler);
endY = (int)((endY) * scaleFactor + filler);
}
else
{
// vertical image
float scaleFactor = picHeight / (float)yMax;
float scaledWidth = xMax * scaleFactor;
float filler = Math.Abs(picWidth - scaledWidth) / 2;
startX = (int)((startX) * scaleFactor + filler);
endX = (int)((endX) * scaleFactor + filler);
startY = (int)(startY * scaleFactor);
endY = (int)(endY * scaleFactor);
}

//if (_once)
//Rectangle ee = new Rectangle(35, 183, 405, 157);
Rectangle ee = new Rectangle(startX, startY, endX - startX, endY - startY);
System.Diagnostics.Debug.WriteLine(startX + ", " + startY + ", " + (endX - startX) + ", " + (endY - startY));
using (Pen pen = new Pen(Color.Red, 2))
{
e.Graphics.DrawRectangle(pen, ee);
}
//_once = false;
}
}

// This class is similar to System.Drawing.Region class
// except that its only rectangular.
// Because all we need is to draw a rectagnle
// around the image this property must
// make it faster, at least I hope so.

class BlackContent
{
internal void FloodFill(Bitmap image)
{
FloodFillPrivate(image, this.left + 1, this.top, 0);
}

// Legendary Flood-Fill algorithm.
// Quite often it ends up with StackOverFlow exception.
// But this class and its rectangularity property
// must prevent this disaster.
// In my experiments I didn't encounter incidents.
void FloodFillPrivate(Bitmap image, int x, int y, int level)
{
if (x >= image.Width || x < 0 || y >= image.Height || y < 0 || this.Contains(x, y) || image.GetPixel(x, y).ToArgb() != Form1.Black)
{
return;
}

this.Include(x, y);

FloodFillPrivate(image, x, y - 1, level + 1);
FloodFillPrivate(image, x, y + 1, level + 1);
FloodFillPrivate(image, x - 1, y, level + 1);
FloodFillPrivate(image, x + 1, y, level + 1);
}

internal BlackContent(int x, int y)
{
this.left = x;
this.right = x;
this.top = y;
this.bottom = y;
}

internal void Include(int x, int y)
{
if (x < this.left)
{
this.left = x;
}
if (this.right < x)
{
this.right = x;
}
if (this.bottom < y)
{
this.bottom = y;
}
if (y < this.top)
{
this.top = y;
}
}

internal bool Contains(int x, int y)
{
return !(x < this.left || x > this.right || y < this.top || y > this.bottom);
}

int left;
internal int Left { get { return this.left; } }
int top;
internal int Top { get { return this.top; } }
int right;
internal int Right { get { return this.right; } }
int bottom;
internal int Bottom { get { return this.bottom; } }

internal int Area
{
get
{
return Width * Height;
}
}

internal int Width
{
get
{
return (this.right - this.left + 1);
}
}

internal int Height
{
get
{
return (this.bottom - this.top + 1);
}
}
}

}

我用ProgressBar看了表演。这个比较快我还必须提到您的图片太大了。

关于c# - 查找图像内容并在其周围绘制矩形,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43722439/

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