How to copy a 2D array with picture greylevels to an image (2) (Views: 100)


I have been developing a program to display and manipulate medical images which consist of 2D arrays of greyscale values as described. As was observed, the Pixels property is way too slow. Here's what I discovered. I think you'll find it a big improvement.


Assuming your data is stored in an array of bytes named TestArray, for example:

TestArray: array[0..127, 0..127] of byte { ... }

ArrayPtr := addr(TestArray); {ArrayPtr: pointer}

In this case we are going to display on the bitmap of a TImage component that has been dropped on the canvas and named Image1.

Image1.Picture.Bitmap.Width := 128;
Image1.Picture.Bitmap.Height := 128;

This is a Windows API function that will copy the bits in TestArray, pointed to by ArrayPtr, into an HBitmap structure, in this case Image1.Picture.Bitmap.Handle.

SetBitmapBits(Image1.Picture.Bitmap.Handle, sizeof(TestArray), ArrayPtr);
Image1.Refresh; {must refresh before changes are displayed}

You still have to deal with the palette, but this technique works great for me.

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