Image Averaging in C#

Replies to This Discussion

Permalink Reply by CC Chiang on November 14, 2016 at 4:46pm

Here's the Gh file

Attachments:

• Test.gh, 657 KB

Permalink Reply by David Rutten on November 14, 2016 at 5:42pm

Could you narrow that down?

If you want to import a bitmap into a C# component (I don't know where you're getting this bitmap instance from though, a different C# component?) you use the system.object hint and then you have to cast the data to the correct type.

Permalink Reply by David Rutten on November 14, 2016 at 5:51pm

I attached a file with two C# components. One which imports an image from a file and resizes it to 50x50 pixels, and another which creates a mesh with coloured vertices.

Attachments:

• bitmapprocess.gh, 5 KB

Permalink Reply by CC Chiang on November 14, 2016 at 6:02pm

Thanks! This is quite different from what I had in mind but it is very interesting.

I've updated my Gh and C# script - now am trying to pull the RGB values from each pixel. I'm not sure if the "c.R = Red;" line should be "c.R = double Red;" and output Red? Thanks!

Attachments:

• Test.gh, 661 KB

Permalink Reply by David Rutten on November 15, 2016 at 5:13am

c.R = double Red;

This is not valid C#. If you want to extract the red, green and blue integer values of a colour, you need to write:

int red = c.R;

int green = c.G;

int blue = c.B;

The equals symbol in C# does not encode equality, it encodes assignment. C# doesn't have a concept of defining two values to be equal to each other. Incidental equality can be tested using == though, for example:

if (c.R == 0)

  print("This colour has no red whatsoever.");

Do note that the GetPixel() and SetPixel() methods are quite slow, because they operate on the 'unlocked' bitmap and a lot of error checking happens each time. One way to speed things up is by locking the bitmap and accessing the data in memory directly, but I recommend you use the GH_MemoryBitmap class which does all the hard work for you.

I'll upload an example of this soon.

Permalink Reply by David Rutten on November 15, 2016 at 5:21am

But first your fixed code. Are you trying to transition from another programming language? Or are you reading C++ tutorials maybe? 

Attachments:

• bitmapTest.gh, 26 KB

Permalink Reply by David Rutten on November 15, 2016 at 5:35am

And here's a way to use GH_MemoryBitmap.

Attachments:

• QuickSampling.gh, 21 KB

Permalink Reply by CC Chiang on November 15, 2016 at 8:27pm

Thank you so much! I am learning C# - thus the basic errors. We'll use the corrected script for now and work on applying image transformations. Thanks again!

Permalink Reply by WP Lee on July 6, 2017 at 7:47am

Anyone knows why the method GetPixel is not available when developing a GH add-on?

I've used the latest rhino visual studio wizard to setup a GH add-on solution and use the assemblies listed below to create a custom component. There are 2 issues:

1. VS wants to simplify the member access of the "Bitmap" to the "Image" class
2. GetPixel method is not recognized.

using System;
using System.Collections.Generic;
using Grasshopper;
using Grasshopper.Kernel;
using Rhino.Geometry;
using Grasshopper.Kernel.Types;

...

  var im = System.Drawing.Bitmap.FromFile("some_filename");

  var color = im.GetPixel(1,1);

Permalink Reply by Vicente Soler on July 6, 2017 at 9:24am

FromFile returns an Image type. GetPixel is part of the Bitmap type.

There are 3 constructors to create a Bitmap from an Image:

https://msdn.microsoft.com/en-us/library/system.drawing.bitmap(v=vs.110).aspx

There's another one that allows you to create a Bitmap directly from a file.

Permalink Reply by WP Lee on July 6, 2017 at 10:19am

tnx, i didn't pay attention enough about the return value

Permalink Reply by David Rutten on July 6, 2017 at 9:28am

In think the two problems might be related. Instead of using var, specifically set the type of im to be a Bitmap. (You may also want to import the System.Drawing namespace)

Bitmap im = new Bitmap("filename");

• ‹ Previous
• 1
• 2
• Next ›
• Page