Databases
StackOverflow2013
Postsdbo
POGetting different bitmap object from same image file
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POGetting different bitmap object from same image file
    primarykey
    data
    text
    <p>I am creating Bitmap object from the same image, but in the end getting different results. It should calculate deviation from the image colors and images are the same so why results are different?</p> <pre><code> double test1 = GetStdDev("C:\\temp\\images\\file.jpg"); Bitmap img = new Bitmap("C:\\temp\\images\\file.jpg"); double test2 = GetStdDev(img); public static double GetStdDev(string imageFileName) { double total = 0, totalVariance = 0; int count = 0; double stdDev = 0; // First get all the bytes using (Bitmap b = new Bitmap(imageFileName)) { BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadOnly, b.PixelFormat); int stride = bmData.Stride; IntPtr Scan0 = bmData.Scan0; unsafe { byte* p = (byte*)(void*)Scan0; int nOffset = stride - b.Width * 3; for (int y = 0; y &lt; b.Height; ++y) { for (int x = 0; x &lt; b.Width; ++x) { count++; byte blue = p[0]; byte green = p[1]; byte red = p[2]; int pixelValue = Color.FromArgb(0, red, green, blue).ToArgb(); total += pixelValue; double avg = total / count; totalVariance += Math.Pow(pixelValue - avg, 2); stdDev = Math.Sqrt(totalVariance / count); p += 3; } p += nOffset; } } b.UnlockBits(bmData); } return stdDev; } private static double GetStdDev(Bitmap img) { double total = 0, totalVariance = 0; int count = 0; double stdDev = 0; // First get all the bytes using (Bitmap b = new Bitmap(img)) { BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadOnly, b.PixelFormat); int stride = bmData.Stride; IntPtr Scan0 = bmData.Scan0; unsafe { byte* p = (byte*)(void*)Scan0; int nOffset = stride - b.Width * 3; for (int y = 0; y &lt; b.Height; ++y) { for (int x = 0; x &lt; b.Width; ++x) { count++; byte blue = p[0]; byte green = p[1]; byte red = p[2]; int pixelValue = Color.FromArgb(0, red, green, blue).ToArgb(); total += pixelValue; double avg = total / count; totalVariance += Math.Pow(pixelValue - avg, 2); stdDev = Math.Sqrt(totalVariance / count); p += 3; } p += nOffset; } } b.UnlockBits(bmData); } return stdDev; } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USReno
    1. USReno
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. CO**1)** Why does `GetStdDev(Bitmap img)` create a new image instead of iterating the one it's given? **2)** Why not just have `GetStdDev(string imageFileName)` load the image and call `GetStdDev(Bitmap img)`?
      singulars
      1. POGetting different bitmap object from same image file
      1. USRotem
    2. COThe problem is that when i call GetStdDev(Bitmap img) it gets wrong result and can't understand why...
      singulars
      1. POGetting different bitmap object from same image file
      1. USReno
    3. COI don't know why there's a difference but I don't understand how either of the methods produces any meaningful result. Are you sure you understand what `Color.ToArgb()` returns?
      singulars
      1. POGetting different bitmap object from same image file
      1. USRotem
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload