EmguCV4中Mat、MCvMat等图像存储类型差异及适用场景咨询

Hey there, I totally get the confusion—Emgu CV’s mix of types can feel overwhelming, especially since the official docs don’t spell this out clearly. Let’s break this down simply, starting with why so many types exist in the first place.

Why Do Multiple Types Exist? #

Emgu CV is a .NET wrapper for OpenCV, so its type system balances three key needs:

1. Direct OpenCV Compatibility: Wrapping raw C++/C types from OpenCV to let you interact with native code or legacy projects.
2. .NET-Friendly Usability: Adding strongly-typed, intuitive wrappers that fit how .NET developers work (no messy pointer handling, type safety).
3. Legacy Support: Keeping older types around to avoid breaking code written for Emgu CV versions before 4.x.

Now let’s dive into each type, what it’s for, and when to use it:

1. Mat #

This is the workhorse of modern Emgu CV, a direct wrapper for OpenCV’s cv::Mat (the de facto standard for image/matrix storage in OpenCV since 2012). It’s a flexible n-dimensional array that can store images, raw pixel data, or numerical matrices.

Use Cases:

• Almost all new Emgu CV code: reading/writing images (CvInvoke.Imread(), CvInvoke.Imwrite()), running image processing algorithms (filters, edge detection, feature matching), and passing data between Emgu CV functions.
• When you need maximum compatibility with OpenCV’s core API—every modern function in Emgu CV supports Mat.

2. Image<TColor, TDepth> #

A .NET-optimized, strongly-typed wrapper specifically for 2D images. Unlike Mat, it enforces type safety for color spaces (e.g., Bgr, Gray, Hsv) and pixel depth (e.g., byte, float). It also includes handy extension methods for common image operations (like resizing, cropping, or pixel-wise manipulation) that feel more natural to .NET devs.

Use Cases:

• When you want to write clean, type-safe image processing code (no casting pixel values manually).
• For quick pixel access or modification: image[0,0] = new Bgr(255,0,0) is way more readable than messing with Mat’s raw data pointers.
• Easily convert to/from Mat whenever you need to use lower-level OpenCV functions: image.Mat gives you the underlying Mat, and myMat.ToImage<Bgr, byte>() converts back.

3. Matrix<TDepth> #

A strongly-typed wrapper for 2D numerical matrices (not images). It’s focused on linear algebra and mathematical operations, with no color space overhead. Think of it as a specialized version of Mat for matrix math.

Use Cases:

• Working with calibration data (camera intrinsic/extrinsic matrices), transformation matrices, or any pure numerical grid.
• Performing linear algebra operations: matrix multiplication, inversion, transposing—Matrix has built-in methods for these that are more intuitive than using Mat’s generic functions.

4. MCvMat #

A wrapper for OpenCV’s old C-style CvMat type, which was replaced by cv::Mat years ago. This is strictly a legacy type in Emgu CV 4.

Use Cases:

• Only if you’re maintaining very old Emgu CV code (from version 2.x or earlier) that relies on CvMat. Avoid using it in new projects—migrate to Mat instead.

5. MIplImage #

Another legacy wrapper, this time for OpenCV’s ancient IplImage structure (a C-style image type that’s long been deprecated in OpenCV). Like MCvMat, it’s only here for backward compatibility.

Use Cases:

• Same as MCvMat: only for legacy code that hasn’t been updated to use Mat or Image<TColor, TDepth>. New projects should ignore this entirely.

6. ScalarArray #

A wrapper for OpenCV’s cv::Scalar, a small fixed-size array (up to 4 elements) used to represent color values, pixel intensities, or small vectors. It’s often used alongside Mat or Image to define colors for drawing operations or set pixel values.

Use Cases:

• Specifying colors for drawing: CvInvoke.Rectangle(myMat, rect, new ScalarArray(new double[] { 0, 255, 0 })) for a green rectangle.
• Setting single-pixel values in a Mat or Image, or representing multi-channel pixel data (e.g., BGR values).

Quick Cheat Sheet for New Projects #

• General image processing: Use Mat (core) or Image<TColor, TDepth> (easier, type-safe).
• Matrix math: Use Matrix<TDepth>.
• Colors/pixel values: Use ScalarArray.
• Ignore: MCvMat and MIplImage unless you’re fixing old code.

内容的提问来源于stack exchange，提问作者user10862935