c#bitmaplockbits
Set white and black pixel depends on brightness
I'm trying to find the needle from these or similar pictures:
My solution is take average brightness of picture and set black and white pixels depends on it. The result is something like this:
I dont need to see numbers and staf there.. only needle but its not big problem when its there. But im using set, get pixel functions and its realy slow i reed something about LockBits metod, i use it for get brightness but i dont know how to use it correct for setpixel. Can anyone help me with my code?..thnx
BitmapData imageData = imgPristroj.LockBits(new Rectangle(0, 0, imgPristroj.Width, imgPristroj.Height), ImageLockMode.ReadOnly, imgPristroj.PixelFormat);
float brightness = 0;
float average;
unsafe
{
try
{
UnmanagedImage Unimg = new UnmanagedImage(imageData);
int pixelSize = (Unimg.PixelFormat == PixelFormat.Format24bppRgb) ? 3 : 4;
byte* p = (byte*)Unimg.ImageData.ToPointer();
for (int y = 0; y < Unimg.Height; y++)
{
for (int x = 0; x < Unimg.Width; x++, p += pixelSize)
{
brightness += Unimg.GetPixel(x, y).GetBrightness();
}
}
average = brightness / (Unimg.Width * Unimg.Height);
}
finally
{
imgPristroj.UnlockBits(imageData); //Unlock
}
}
img19 = (Bitmap)imgPristroj.Clone();
for (int y = 0; y < img19.Height; y++)
{
for (int x = 0; x < img19.Width; x++)
{
if (img19.GetPixel(x, y).GetBrightness() > average)
{
img19.SetPixel(x, y, Color.White);
}
else
{
img19.SetPixel(x, y, Color.Black);
}
}
}
Edit2: This is my whole code..
float brightness = 0;
float average = 0;
PixelUtil pixelUtil2 = new PixelUtil((Bitmap)imgPristroj.Clone());
pixelUtil2.LockBits();
for (int y = 0; y < imgPristroj.Height; y++)
{
// for each pixel
for (int x = 0; x < imgPristroj.Width; x++)
{
brightness += pixelUtil2.GetPixel(x, y).GetBrightness();
}
}
average = brightness / (imgPristroj.Width * imgPristroj.Height);
pixelUtil2.UnlockBits();
img19 = (Bitmap)imgPristroj.Clone();
Crop cfilter1 = new Crop(new Rectangle(0, (int)(pix * 1.6), img19.Width, (int)(pix * 3)));
img19 = cfilter1.Apply(img19);
PixelUtil pixelUtil = new PixelUtil(img19);
pixelUtil.LockBits();
for (int y = 0; y < img19.Height; y++)
{
for (int x = 0; x < img19.Width; x++)
{
if (pixelUtil.GetPixel(x, y).GetBrightness() >= average)
{
pixelUtil.SetPixel(x, y, Color.White);
}
else
{
pixelUtil.SetPixel(x, y, Color.Black);
}
}
}
pixelUtil.UnlockBits();
string filepath = Environment.CurrentDirectory;
string fileName = System.IO.Path.Combine(filepath, @"img" + ".bmp");
img19.Save(fileName);
I get this bitmap with color pixels, can you tell me why?
And when i use red color.. not black... (pixelUtil.SetPixel(x, y, Color.Red);) i have got this funny pic. (differnt size is OK..)
Solution
You can try using marshaling: It's quite fast. (You just need to copy-paste this)
public class PixelUtil
{
Bitmap source = null;
IntPtr Iptr = IntPtr.Zero;
BitmapData bitmapData = null;
public byte[] Pixels { get; set; }
public int Depth { get; private set; }
public int Width { get; private set; }
public int Height { get; private set; }
/// <summary>
/// Pixel marshaling class, use this to get and set pixels rapidly.
/// </summary>
/// <param name="source">The Bitmap to work with</param>
public PixelUtil(Bitmap source)
{
this.source = source;
}
/// <summary>
/// Lock bitmap data
/// </summary>
public void LockBits()
{
try
{
// Get width and height of bitmap
Width = source.Width;
Height = source.Height;
// get total locked pixels count
int PixelCount = Width * Height;
// Create rectangle to lock
var rect = new Rectangle(0, 0, Width, Height);
// get source bitmap pixel format size
Depth = System.Drawing.Image.GetPixelFormatSize(source.PixelFormat);
// Check if bpp (Bits Per Pixel) is 8, 24, or 32
if (Depth != 8 && Depth != 24 && Depth != 32)
{
throw new ArgumentException("Only 8, 24 and 32 bpp images are supported.");
}
// Lock bitmap and return bitmap data
bitmapData = source.LockBits(rect, ImageLockMode.ReadWrite,
source.PixelFormat);
// create byte array to copy pixel values
int step = Depth / 8;
Pixels = new byte[PixelCount * step];
Iptr = bitmapData.Scan0;
// Copy data from pointer to array
Marshal.Copy(Iptr, Pixels, 0, Pixels.Length);
}
catch (Exception)
{
throw;
}
}
/// <summary>
/// Unlock bitmap data
/// </summary>
public void UnlockBits()
{
try
{
// Copy data from byte array to pointer
Marshal.Copy(Pixels, 0, Iptr, Pixels.Length);
// Unlock bitmap data
source.UnlockBits(bitmapData);
}
catch (Exception)
{
throw;
}
}
/// <summary>
/// Get the color of the specified pixel
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <returns></returns>
public Color GetPixel(int x, int y)
{
Color clr = Color.Empty;
// Get color components count
int cCount = Depth / 8;
// Get start index of the specified pixel
int i = ((y * Width) + x) * cCount;
if (i > Pixels.Length - cCount)
throw new IndexOutOfRangeException();
if (Depth == 32) //For 32 bpp get Red, Green, Blue and Alpha
{
byte b = Pixels[i];
byte g = Pixels[i + 1];
byte r = Pixels[i + 2];
byte a = Pixels[i + 3]; // a
clr = Color.FromArgb(a, r, g, b);
}
if (Depth == 24) //For 24 bpp get Red, Green and Blue
{
byte b = Pixels[i];
byte g = Pixels[i + 1];
byte r = Pixels[i + 2];
clr = Color.FromArgb(r, g, b);
}
if (Depth == 8) //For 8 bpp get color value (Red, Green and Blue values are the same)
{
byte c = Pixels[i];
clr = Color.FromArgb(c, c, c);
}
return clr;
}
/// <summary>
/// Set the color of the specified pixel
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="color"></param>
public void SetPixel(int x, int y, Color color)
{
//Get color components count
int cCount = Depth / 8;
//Get start index of the specified pixel
int i = ((y * Width) + x) * cCount;
if (Depth == 32) //For 32 bpp set Red, Green, Blue and Alpha
{
Pixels[i] = color.B;
Pixels[i + 1] = color.G;
Pixels[i + 2] = color.R;
Pixels[i + 3] = color.A;
}
if (Depth == 24) //For 24 bpp set Red, Green and Blue
{
Pixels[i] = color.B;
Pixels[i + 1] = color.G;
Pixels[i + 2] = color.R;
}
if (Depth == 8) //For 8 bpp set color value (Red, Green and Blue values are the same)
{
Pixels[i] = color.B;
}
}
}
You can call like this:
public void Example(Bitmap image)
{
PixelUtil pixelUtil = new PixelUtil(image);
pixelUtil.LockBits();
Color firstPixel = pixelUtil.GetPixel(0, 0);
pixelUtil.SetPixel(0, 0, Color.White);
//Don't forget to unlock!
pixelUtil.UnlockBits();
}
EDIT:
Not sure how are you saving the image, but it Works fine for me:
public Form1()
{
InitializeComponent();
Bitmap image1 = new Bitmap(@"C:\Users\Nicke Manarin\Desktop\YEeJO.png");
BlackWhite(image1);
}
public void BlackWhite(Bitmap image)
{
PixelUtil pixelUtil = new PixelUtil(image);
pixelUtil.LockBits();
for (int y = 0; y < image.Height; y++)
{
for (int x = 0; x < image.Width; x++)
{
if (pixelUtil.GetPixel(x, y).GetBrightness() > 0.5)
{
pixelUtil.SetPixel(x, y, Color.White);
}
else
{
pixelUtil.SetPixel(x, y, Color.Black);
}
}
}
pixelUtil.UnlockBits();
pictureBox1.Image = image;
image.Save(@"C:\Users\Nicke Manarin\Desktop\YEeJO2.png");
}
