Getting A pointer to the first Pixel of the Image without Instantiating a Collection

[jdmsolarius]

Is there any way to get a Pointer to the First Pixel in the image without actually Materializing a Collection of Pixels? I know how to do this in System.Drawing and in OpenCV but I either don't know how or I'm doing it wrong in Image Magick.
E.G.
ushort* pixelPointer = (ushort*)image.GetPixelsUnsafe().GetAreaPointer(0, 0, width, height); _I don't actually want the Pixels, I can get references to them using Pointer Arithmetic I cannot do that thought unless I know the Address of the first Pixel. To make matter's worse I also have Create a MagickGeometry object behind the scenes (either directly or by providing coordinates, so I'm Creating a Geometry and then Materializing a Collection when all I want is a pointer.

E.G. (for OpenCV Mat's).

image.Ptr(0); is First Pixel

(for BitmapData bmp)

bmp.Scan0 is First Pixel

[dlemstra]

With GetAreaPointer(0, 0, width, height) you are telling ImageMagick that you want to get a pointer to this area. Under the hood this does the same as getting the first pixel that as been loaded in memory.

[jdmsolarius]

Thanks for the reply! I understand that much, and I may not be doing it right but it seems to me that I cannot call that method (GetAreaPointer) on a MagickImage, I have to actually create a Collection of Pixels as a Precondition to getting the Pointer. E.G.

ushort* pixelPointer = (ushort*)image.**GetPixels()**.GetAreaPointer(0, 0, height, width);
ushort* pixelPointer = (ushort*)image.**GetPixelsUnsafe()**.GetAreaPointer(0, 0, height, width);

but this is wasteful because I am materializing Millions or even 10's of Millions of Pixels each with several channels when I am not interested at all in the collection, only the memory address of the first Pixel. (From there I can calculate Offsets.)

//Create Image in OpenCV
Mat image = new Mat(ColorSpace.Gray, 0,0)
//Get a Pointer to the first Pixel in that Image
ushort* PixelPtr = image.Ptr(0)`

which is very convenient because it doesn't make me get a UShort Array or a Byte Array of the Pixels in order to get a reference. Or is there a way to call GetAreaPointer or something similar on the MagickImage instead of on a PixelCollection?

[jdmsolarius]

what about ptrFirstPixel property or a PtrScan0 property with the logic (GetPixelsUnsafe().GetAreaPointer(0,0,image.width,image.height) just abstracted away in the getter? That would be really convenient

[dlemstra]

There will not be a new property on the MagickImage class. The pixel related methods will remain on the PixelCollection classes. The only thing I can do is provide you with a method that gets the whole area. But you will still need to use the GetPixelsUnsafe method.

[jdmsolarius]

This is not without Precedent, for Example I can call Image.SortPixels(). Which Avoids the Overhead of having to Instantiate the Collection in order to sort it. The VirtualPixelMethod Property works in the same fashion. That being said, if you do not want to add any more Pixel Related methods to the MagickImage Class then ideally one of the Pixel Collections would be Lazy in Nature. I suppose the core issue is that "GetPixelCollectionUnsafe" causes a Massive Iteration involving Millions of Pixels. It would be nice if I could Get an IEnumerable and I could get Call GetAreaPixel on that. This could even be done without calling any C Code since it is just a State Machine Promising to Yield Pixels if they are asked for. Currently I can either get Millions of Pixels or None.

[dlemstra]

There is no iteration happening. You are only getting an api to access the pixels. I have now tried to explain this multiple times but I am not sure what kind of wording I should use to make this clear to you. The PixelCollection is IEnumerable but the pixels will only be iterated when you are doing that yourself. The GetAreaPointer method returns your a pointer to the native pixel area that you specified.

[jdmsolarius]

I Apologize I missed that or did not understand that. In that case the current methods should be sufficient. Thank you for taking the time to explain it to me. I appreciate your hard work and did not mean to seem combative