查找图像内容并在其周围绘制矩形
关于
我正在使用WinForms。在我的表单中，我有一个picturebox。 picturebox尺寸模式设置为zoom。我使用picturebox来查看TIF图像。 TIF图像为灰度（仅黑白）。
我的应用程序
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斑点/点。这会抛弃我的应用程序。它不知道图像内容的开始和结束位置。如果文档有斑点/点，我怎样才能找到TIF文档的内容并在其周围画一个矩形？
关于文件
- 仅限黑白（1位深度）
- TIF文件
- 文档始终包含字母和数字
- 字母和数字总是比斑点/点数大
- 即使在内容 中，图像上也可能有多个点
- 背景总是白色
- 内容始终为黑色
- 斑点也是黑色
下载测试图片链接：
•文件删除器： http://www.filedropper.com/test-tifs
•快速分享 https://ufile.io/2qiir
我找到了什么
根据我的研究，我发现AForge.Imaging库有许多成像过滤器，可能有助于我实现目标。我正在考虑使用中值滤波器去除斑点/点，或者使用其他滤波器来获得所需的结果。
我尝试过什么
我尝试应用AForge库中的中值滤波器来摆脱斑点，但只是摆脱了一些斑点。我不得不重复多次回复过滤器以摆脱大部分的点找到内容，但仍然很难找到内容。这种方法对我来说效果不佳。
指向AForge过滤器的链接： 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;
}
}
内容周围没有任何斑点和点的Tif文件
内容周围有斑点和点的Tif文件
示例图片1：
示例图片2
：
示例图片3
3 个答案:
答案 0 :(得分：1)
解决方案可能是找到黑色像素区域。找到黑色像素时，检查相邻像素的颜色并创建黑色像素区域。当区域足够大时，可以将其视为内容。下面的伪代码说明了这一点。但它是一种资源密集型解决方案，至少应该进行优化。
private List<List<Point>> areas = new List<List<Point>>();
public void PopulateAreas()
{
//Find all the areas
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())
{
//Found a black pixel, check surrounding area
var area = new List<Point>();
area.Add(new Point(x, y));
areas.Add(area);
AppendSurroundingPixelsToArea(area, x, y);
}
}
}
var startX = Int32.MaxValue;
var startY = Int32.MaxValue;
var endX = Int32.MinValue;
var endY = Int32.MinValue;
//Loop through list of areas.
foreach (var area in areas)
{
//Minimum size of area
if (area.Count > 5)
{
var minx = area.Min(p => p.X);
if (area.Min(p => p.X) < startX)
startX = minx;
//Do the same for the others...
}
}
}
public void AppendSurroundingPixelsToArea(List<Point> area, int startX, int startY)
{
for(var x = startX - 1; x <= startX + 1; x++)
for (var y = startY - 1; y <= startY + 1; y++)
{
if ((x != 0 || y != 0) && IsBlackPixel(bmp, x, y))
{
//Add to the area
if (PointDoesNotExistInArea(area, x, y))
{
area.Add(new Point(x, y));
AppendSurroundingPixelsToArea(area, x, y);
}
}
}
}
答案 1 :(得分：1)
以下实验似乎符合您的所有要求。
我将以下控件放到Form1
上一个MenuStrip：Docking = Top，有2个MenuItems - 一个用于打开文件，第二个用于运行算法
进度条：Docking = Top，观察加载和算法的性能
具有Docking = Fill和AutoScroll = true
的面板面板中的图片，点（0,0），其余部分默认为。 SizeMode =正常。
<强>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;
}
}
}
＆＃34; this.pictureBox1.Size = image.Size;＆＃34;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Zoom。
更新2
我尝试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);
}
}
}
}
我观看了ProgressBar的表现。这个比较快。 我还必须提到你的图像太大了。
答案 2 :(得分：0)
我有解决方案，
我建议“柯达影像专业人士”。这是显示多页tiff文件的查看器。具有许多功能，如：注释，反转颜色，旋转图像......等等，这些都是内置功能。</ p>
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