What type of image is this?

[fractalengine]

I have been trying to reverse engineer a small hardware scanning device. The vendor has a DLL with a function called "GetImageData" that I've been executing in VB.NET

It is defined as below:

GetImageData(imageData_out as String, pWitdh as Uinteger, pHeight as Uinteger) as Boolean

Right after calling the function I execute the following:

Text.ASCIIEncoding.Default.GetBytes(imageData_out)

Which always returns an Array of 8192 bytes (regardless of the width, height). After looking at the byte array I noticed only following 10 numbers re-occurring:

Byte - # occurrence in array
63 -> 3894
0 -> 2677
32 -> 592
255 -> 313
64 -> 302
96 -> 221
160 -> 81
134 -> 71
192 -> 65
48 -> 21

This is typical with each scan with some variation in the counts.

I am assuming that it returns some sort of BITMAP image. Possibly black and white with representation of how dark or light each pixel is? Anybody have an idea what type of image is being returned, or how I can go about displaying the data that comes back as an image?

[Frinavale]

Contact the vendor and get their documentation on the SDK that they have provided to you.

[fractalengine]

Well that's the worst part of it all. The vendor doesn't exist anymore, and their is no documentation or SDK, just a DLL that is used by their application. This is just a shot in the dark at reverse engineering their product.

[Plater]

Is this really the case: imageData_out as String
I can't believe (even with VB) that someone would return data as a string like that?

[fractalengine]

@Plater
my thoughts exactly.. When I imported the DLL that's what the object browser reports it as. I assume it's a IntPtr to the image data but not quite sure how to construct the image. After digging around I believe it would be a 8bpp image.

[Plater]

Have you tried creating a Bitmap class from it?
You can make a MemoryStream from a byte[] and try to construct the Bitmap object with it using Bitmap.FromStream(myMemoryStream)

See if it can figure it out?

[fractalengine]

@Plater
"It throws a Parameter is not valid" exception when trying to read from the stream.

:(