How to check if BMP is a monochrome or not ?

[piyushmeshram2014]

Hi Team,
I am new to SkiaSharp and looking for a way to validate if my bmp image is monochrome or not?
I am doing it something like this

var bmpImage = SKBitmap.Decode(contentData);
if(bmpImage.Info.BitsPerPixel != 1)
   throw new Exception(..)

The BitPerPixel always gives "32" , even for a monochrome image where I am expecting it to be "1".Kindly help

[mattleibow]

You can try use SKCodec directly. Using SKBitmap actually decodes and consumes memory. And then it decodes into a ready to draw format - hence the 32 bits.

The code will allow you to open the image and read info about the image without actually consuming memory or changing bits.

[piyushmeshram2014]

It still gives 32 with SKCodec

[IldarKhayrutdinov]

Maybe help you ImageSharp .

BmpMetadata contains accurate BmpBitsPerPixel.

Reading only image info example (without fully loading):
IImageInfo imageInfo = Image.Identify(stream);
https://github.com/SixLabors/ImageSharp/blob/13897ae4c59da50c37a017a4d21fbe80ae1bdde1/tests/ImageSharp.Tests/Formats/Bmp/BmpMetadataTests.cs#L43-L45