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Unity: GetPixels() always results in the colour black across whole image

I have an image (attached) which I'm using as a test. I'm trying to get and store all the colours of each pixel in an array.
I use the below code to do this;
Texture2D tex = mapImage.mainTexture as Texture2D;
int w = tex.width;
int h = tex.height;
Vector4[,] vals = new Vector4[w, h];
Color[] cols = tex.GetPixels();
for (int y = 0; y < h; y++)
{
for (int x = 0; x < w; x++)
{
if(cols[y+x] != Color.black)
{
Debug.Break();
}
vals[x, y] = cols[(y + x)];
}
}
Where mapImage is a public Material variable which I drag in into the scene on the prefab. As you can see, I've added a debug test there to pause the editor if a non-black colour is reached. This NEVER gets hit ever.
Interestingly, I've got another script which runs and tells me the colour values (GetPixel()) at the click position using the same image. It works fine (different methods, but both ultimately use the same material)
I'm at a loss as to why GetPixels() is always coming out black?
I've also been considering just loading the image data into a byte array, then parsing the values into a Vector4, but hoping this will work eventually.

You aren't indexing into the Color array properly. With the indices you are using, y+x, you keep checking the same values on the lowest rows of the texture, never getting past a certain point.
Instead, when calculating the index, you need to multiply the row that you are on by the row length and add that to the column you are on:
Texture2D tex = mapImage.mainTexture as Texture2D;
int w = tex.width;
int h = tex.height;
Vector4[,] vals = new Vector4[w, h];
Color[] cols = tex.GetPixels();
for (int y = 0; y < h; y++)
{
for (int x = 0; x < w; x++)
{
int index = y * w + x;
vals[x, y] = cols[index];
}
}
From the documentation on GetPixels:
The returned array is a flattened 2D array, where pixels are laid out left to right, bottom to top (i.e. row after row). Array size is width by height of the mip level used. The default mip level is zero (the base texture) in which case the size is just the size of the texture. In general case, mip level size is mipWidth=max(1,width>>miplevel) and similarly for height.

C# How to nextline in e.Drawing when printing images

I'm generating a barcode depending on how many inputs that the user set in the numericUpDown control. The problem is when generating a lot of barcodes, the other barcodes cannot be seen in the printpreviewdialog because it I cannot apply a nextline or \n every 4-5 Images.
int x = 0, y = 10;
for (int i = 1; i <= int.Parse(txtCount.Text); i++)
{
idcount++;
connection.Close();
Zen.Barcode.Code128BarcodeDraw barcode = Zen.Barcode.BarcodeDrawFactory.Code128WithChecksum;
Random random = new Random();
string randomtext = "MLQ-";
int j;
for (j = 1; j <= 6; j++)
{
randomtext += random.Next(0, 9).ToString();
Image barcodeimg = barcode.Draw(randomtext, 50);
resultimage = new Bitmap(barcodeimg.Width, barcodeimg.Height + 20);
using (var graphics = Graphics.FromImage(resultimage))
using (var font = new Font("Arial", 11)) // Any font you want
using (var brush = new SolidBrush(Color.Black))
using (var format = new StringFormat() { Alignment = StringAlignment.Center, LineAlignment = StringAlignment.Far}) // Also, horizontally centered text, as in your example of the expected output
{
graphics.Clear(Color.White);
graphics.DrawImage(barcodeimg, 0, 0);
graphics.DrawString(randomtext, font, brush, resultimage.Width / 2, resultimage.Height, format);
}
x += 25;
}
e.Graphics.DrawImage(resultimage, x, y);
}

There's no "new lines" in rasterized graphics. There's pixels. You've got the right idea, every n number of images, add a new line. But since you're working with pixels, let's say every 4 images you're going to need to add a vertical offset by modifying the y coordinate of all your graphics draw calls. This offset, combined with a row height in pixels could look something like this:
var rowHeight = 250; // pixels
var maxColumns = 4;
var verticalOffset = (i % maxColums) * rowHeight;
Then, when you can supply a y coordinate, starting at or near 0, add the vertical offset to it.

How to detect the upmost black pixel

I have an application that creates an image from a text inputed by the user. In that image, I want to detect where is the beginning of the letters in the top so I can stamp my brand's logo and crop image accordingly.
This is what I tried so far, but can't get it to work...
Bitmap myBitmap = new Bitmap(Image.FromFile(#"C:\Users\me\Desktop\test_textimage.jpg"));
for (int j = 0; j < 2000; j++) // loops Y axis
{
for (int i = 0; i < 3500; i++) // loops X axis
{
System.Drawing.Color color = myBitmap.GetPixel(i, j);
if (color == System.Drawing.Color.Black)
{ // breakpoint here... it never hits...
}
}
}
I am 100% sure the image is black font into white background. Tested into photoshop.
Can anyone help? Thanks.

How can I save the location of every single pixel of my image in c#?

I am writing a programme that I need to save the location of every single pixel in my bitmap image in an array and later on in need to for example randomly turn off 300 of black pixels randomly. However I am not sure how to do that. I have written the following code but of course it does not work. Can anyone please tell me the right way of doing that?

The locations of every pixel are constant (every pixel has exactly one x and one y coordinate) so the requirement of save the location of every single pixel is vague.
I guess what you try to do is: Turn 300 pixels in an image black, but save the previous color so you can restore single pixels?
You could try this:
class PixelHelper
{
public Point Coordinate;
public Color PixelColor;
}
PixelHelper[] pixelBackup = new PixelHelper[300];
Random r = new Random();
for (int i = 0; i < 300; i++)
{
int xRandom = r.Next(bmp.Width);
int yRandom = r.Next(bmp.Height);
Color c = bmp.GetPixel(xRandom, yRandom);
PixelHelper[i] = new PixelHelper() { Point = new Point(xRandom, yRandom), PixelColor = c };
}
After that the pixelBackup array contains 300 objects that contain a coordinate and the previous color.
EDIT: I guess from the comment that you want to turn 300 random black pixels white and then save the result as an image again?
Random r = new Random();
int n = 0;
while (n < 300)
{
int xRandom = r.Next(bmp.Width);
int yRandom = r.Next(bmp.Height);
if (bmp.GetPixel(xRandom, yRandom) == Color.Black)
{
bmp.SetPixel(xRandom, yRandom, Color.White);
n++;
}
}
bmp.Save(<filename>);
This turns 300 distinct pixels in your image from black to white. The while loop is used so I can increase n only if a black pixel is hit. If the random coordinate hits a white pixel, another pixel is picked.
Please note that this code loops forever in case there are less than 300 pixels in your image in total.

The following will open an image into memory, and then copy the pixel data into a 2d array. It then randomly converts 300 pixels in the 2d array to black. As an added bonus, it then saves the pixel data back into the bitmap object, and saves the file back to disk.
I edited the code to ensure 300 distinct pixels were selected.
int x = 0, y = 0;
///Get Data
Bitmap myBitmap = new Bitmap("mold.jpg");
Color[,] pixelData = new Color[myBitmap.Width, myBitmap.Height];
for (y = 0; y < myBitmap.Height; y++)
for (x = 0; x < myBitmap.Width; x++)
pixelData[x,y] = myBitmap.GetPixel(x, y);
///Randomly convert 3 pixels to black
Random rand = new Random();
List<Point> Used = new List<Point>();
for (int i = 0; i < 300; i++)
{
x = rand.Next(0, myBitmap.Width);
y = rand.Next(0, myBitmap.Height);
//Ensure we use 300 distinct pixels
while (Used.Contains(new Point(x,y)) || pixelData[x,y] != Color.Black)
{
x = rand.Next(0, myBitmap.Width);
y = rand.Next(0, myBitmap.Height);
}
Used.Add(new Point(x, y)); //Store the pixel we have used
pixelData[x, y] = Color.White;
}
///Save the new image
for (y = 0; y < myBitmap.Height; y++)
for (x = 0; x < myBitmap.Width; x++)
myBitmap.SetPixel(x, y, pixelData[x, y]);
myBitmap.Save("mold2.jpg");

Improving perfomance for randomly created panels

So what I'm trying to do is create like a random image from panels of different colors. The user can choose how many panels (i.e. pixels) he wants to have and the number of different colors and then the program automatically generates that image. I'd really like to use panels for this because I will need this picture later on and need to modify every single pixel. As I'm comfortable with panels, I'd like to keep them and not use anything else.
So here's the code I'm using to create this panels:
//Creates two lists of panels
//Add items to list so that these places in the list can be used later.
//nudSizeX.Value is the user-chosen number of panels in x-direction
for (int a = 0; a < nudSizeX.Value; a++)
{
horizontalRows.Add(null);
}
//nudSizeY.Value is the user-chosen number of panels in y-direction
for (int b = 0; b < nudSizeY.Value; b++)
{
allRows.Add(null);
}
for (int i = 0; i < nudSizeY.Value; i++)
{
for (int j = 0; j < nudSizeX.Value; j++)
{
// new panel is created, random values for background color are assigned, position and size is calculated
//pnlBack is a panel used as a canvas on whoch the other panels are shown
Panel pnl = new Panel();
pnl.Size = new System.Drawing.Size((Convert.ToInt32(pnlBack.Size.Width)) / Convert.ToInt32(nudSizeX.Value), (Convert.ToInt32(pnlBack.Size.Height) / Convert.ToInt32(nudSizeY.Value)));
pnl.Location = new Point(Convert.ToInt32((j * pnl.Size.Width)), (Convert.ToInt32((i * pnl.Size.Height))));
//There are different types of panels that vary in color. nudTypesNumber iis the user-chosen value for howmany types there should be.
int z = r.Next(0, Convert.ToInt32(nudTypesNumber.Value));
//A user given percentage of the panels shall be free, i.e. white.
int w = r.Next(0, 100);
if (w < nudPercentFree.Value)
{
pnl.BackColor = Color.White;
}
//If a panel is not free/white, another rendom color is assigned to it. The random number determinig the Color is storede in int z.
else
{
switch (z)
{
case 0:
pnl.BackColor = Color.Red;
break;
case 1:
pnl.BackColor = Color.Blue;
break;
case 2:
pnl.BackColor = Color.Lime;
break;
case 3:
pnl.BackColor = Color.Yellow;
break;
}
}
//Every panel has to be added to a list called horizontal rows. This list is later added to a List<List<Panel>> calles allRows.
horizontalRows[j] = (pnl);
//The panel has also to be added to the "canvas-panel" pnl back. The advantage of using the canvas panel is that it is easier to determine the coordinates on this panel then on the whole form.
pnlBack.Controls.Add(pnl);
}
allRows[i] = horizontalRows;
}
As you might imagine, this is very slow when creating a checkerboard of 99x99 because the program has to loop through the process nearly 10000 times.
What would you to to improve performance? I said I'd like to keep doing it with panels because I'm comfortable with them, but if using panels is even more dumb than I thought, I'm open to other options. The program gets slower and slower the more panels it has already created. I guess that's because of the adding to the list that grows larger and larger?
This is how the output looks right now:
This is what I want to do with my "picture" later: I basically want to do Schellings model. That model shows how different groups of people (i.e. different colors) segregate when they want to have a certain percentage of people around them that belong to their group. That means that later on I have to be able to check for each of the panels/pixels what the neighbours are and have to be able to be able to change color of each pixel individually.
I don't want a ready solution, I'm just hoping for tips how to improve the speed of the picture-creating process.
Thank you very much

Instead of using Panels use a matrix to store your colors and other information you need.
In OnPaint event, use this matrix to draw the rectangles using GDI+.
Here is an example on how to draw 10x10 "pixels" if you have a matrix that contains colors:
private void myPanel_Paint(object sender, PaintEventArgs e)
{
for (var y=0; y < matrix.GetUpperBound(0); y++)
for (var x=0; x < matrix.GetUpperBound(1); x++)
{
var Brush = new SolidBrush(matrix[y,x]);
e.Graphics.FillRectangle(Brush, new Rectangle(x*10, y*10, 10, 10));
}
}

Use a picturebox to do your drawing. You've already got the code to see where each panel should be, just change it to draw a rectangle at each position. This way, you'll just be drawing a few rectangles on a board instead of working with 10.000 GUI objects.
Oh, keep your model/logic and view separated. Keep one matrix with all your information and just use a "Paint method" to draw it.
Your model could look something like this:
MyPanel[,] panels;
class MyPanel
{
Color color;
}
This way it's easy to check all neighbours of a panel, just check in the panels matrix.
And your view should just do something like this:
class View
{
Paint(MyPanel[,] panels)
{
//Draw
}
}

I think your best approach here is to write a custom Control class to draw the squares, and a custom collection class to hold the squares.
Your square collection class could look like this:
public sealed class ColouredSquareCollection
{
readonly int _width;
readonly int _height;
readonly Color[,] _colours;
public ColouredSquareCollection(int width, int height)
{
_width = width;
_height = height;
_colours = new Color[_width, _height];
intialiseColours();
}
public Color this[int x, int y]
{
get { return _colours[x, y]; }
set { _colours[x, y] = value; }
}
public int Width
{
get { return _width; }
}
public int Height
{
get { return _height; }
}
void intialiseColours()
{
for (int y = 0; y < _height; ++y)
for (int x = 0; x < _width; ++x)
_colours[x, y] = Color.White;
}
}
Then you write a custom control. To do so, add a new Custom control via Add new item -> Windows Forms -> Custom Control, and call it ColouredSquareHolder.
Then change the code to look like this. Notice how it is responsible for drawing all the squares:
public sealed partial class ColouredSquareHolder: Control
{
ColouredSquareCollection _squares;
public ColouredSquareHolder()
{
ResizeRedraw = true;
DoubleBuffered = true;
InitializeComponent();
}
public ColouredSquareCollection Squares
{
get
{
return _squares;
}
set
{
_squares = value;
Invalidate(); // Redraw after squares change.
}
}
protected override void OnPaint(PaintEventArgs pe)
{
base.OnPaint(pe);
if (_squares == null)
return;
int w = Width;
int h = Height;
int nx = _squares.Width;
int ny = _squares.Height;
var canvas = pe.Graphics;
for (int yi = 0; yi < ny; ++yi)
{
for (int xi = 0; xi < nx; ++xi)
{
int x1 = (xi*w)/nx;
int dx = ((xi + 1)*w)/nx - x1;
int y1 = (yi*h)/ny;
int dy = ((yi+1)*h)/ny - y1;
using (var brush = new SolidBrush(_squares[xi, yi]))
canvas.FillRectangle(brush, x1, y1, dx, dy);
}
}
}
}
Now you'll need to set up the square collection, add it to a ColouredSquareHolder and then add that to a form.
Firstly, add the ColouredSquareHolder to your test program and compile it so that it will show up in the Toolbox for the Windows Forms Editor.
Then create a new default Form called Form1, and from the Toolbox add a ColouredSquareHolder to it, and set the ColouredSquareHolder to Dock->Fill. Leave it called the default colouredSquareHolder1 for this demonstration.
Then change your Form1 class to look like this:
public partial class Form1: Form
{
readonly ColouredSquareCollection _squares;
readonly Random _rng = new Random();
public Form1()
{
InitializeComponent();
_squares = new ColouredSquareCollection(100, 100);
for (int x = 0; x < _squares.Width; ++x)
for (int y = 0; y < _squares.Height; ++y)
_squares[x, y] = randomColour();
colouredSquareHolder1.Squares = _squares;
}
Color randomColour()
{
return Color.FromArgb(_rng.Next(256), _rng.Next(256), _rng.Next(256));
}
}
Run your program and see how much faster it is at drawing the squares.
Hopefully this will give you the basis for something that you can build on.
Note: If you change the colours in the square collection, you will need to call .Invalidate() on the control in the form to make it redraw with the new colours.

well I suggest you using GDI+ instead , you can store your colors in a 2 dimensional array so you can draw the desired image based on that and also you can loop through them for further process , take a look at this code and also the demo project :
as you mentioned that you're not familiar with gdi+ , there is a demo project included so you can check it yourself and see how It's done in gdi+ :
demo project : ColorsTableDemoProject
Color[,] colorsTable;
Bitmap b;
Graphics g;
int size = 80; // size of table
int pixelWidth = 5; // size of each pixel
Random r = new Random();
int rand;
// CMDDraw is my Form button which draws the image
private void CMDDraw_Click(object sender, EventArgs e)
{
colorsTable = new Color[size, size];
pictureBox1.Size = new Size(size * pixelWidth, size * pixelWidth);
b = new Bitmap(size * pixelWidth, size * pixelWidth);
g = Graphics.FromImage(b);
for (int y = 0; y < size; y++)
{
for (int x = 0; x < size; x++)
{
rand = r.Next(0, 4);
switch (rand)
{
case 0: colorsTable[x, y] = Color.White; break;
case 1: colorsTable[x, y] = Color.Red; break;
case 2: colorsTable[x, y] = Color.Blue; break;
case 3: colorsTable[x, y] = Color.Lime; break;
default: break;
}
g.FillRectangle(new SolidBrush(colorsTable[x, y]), x * pixelWidth, y * pixelWidth, pixelWidth, pixelWidth);
}
}
pictureBox1.Image = b;
}