Why is the image type obtained by loading a grayscale image using Image<L8>.Load in Rgba32 format? How can I obtain the actual data format?

[liu7923032]

Prerequisites

• I have written a descriptive issue title
• I have verified that I am running the latest version of ImageSharp
• I have verified if the problem exist in both DEBUG and RELEASE mode
• I have searched open and closed issues to ensure it has not already been reported

ImageSharp version

3.119.1

Other ImageSharp packages and versions

3.119.1

Environment (Operating system, version and so on)

window10

.NET Framework version

.NET10

Description

I hope to obtain the true grayscale image format, as my image size is too large(1G). However, after loading through ImageSharp, the image has been converted to RGBA32 format, resulting in a significant increase in memory usage

Steps to Reproduce

1. any gray image
2. var image = Image<L8>.Load(file)

Images

No response

[JimBobSquarePants]

I’ve converted this into a discussion. Issues are for defects only.

What you are describing is fundamentally impossible. The TPixel generic parameter describes the layout, in memory, of the decoded image. L8 comprises of a single byte value representing luminance so in no way can be RGBA32.

[liu7923032]

Sorry, I wrote the wrong version number for ImageSharp. The correct version number is 3.1.12. The image type I see with ImageJ is 8-bit, but the type loaded by ImageSharp is actually Rgba32

[JimBobSquarePants]

No it isn’t. If you used L8 as the type parameter then it is L8.

Do you understand how generics work?

[liu7923032]

It's just two lines of code. I don't know what I did wrong

[liu7923032]

original image
Gray.bmp

[tocsoft]

your calling the wrong API

you want Image.Load<L8>(filename) not Image<L8>.Load(filename) (which is just the same as calling Image.Load(filename)) and thus uses the default type for the image.

[liu7923032]

@tocsoft Thank very much