Alpha image data size doesn't match to image data size

Hello,
I have two images: img1.png and img2.png. Both are 32bit images with transparency.
With method RasterImage.CreateAlphaImage() i'm creating alpha image for both files.
The RasterImage.DataSize of original image should be equal to data size of alpha image multiple by 4.
I have problem with img1.png, because data size values doesn't match.
Is there something wrong with my file or i'm doing someting wrong?

I'm using .NET Leadtools 17.5.
Images int attachment

The RasterImage.DataSize of original image should NOT always be equal to data size of alpha image multiplied by 4.
The reason is that images in LEADTOOLS are stored in memory so that the BytesPerLine are always a multiple of 4. Since the original image 32-bit, which means 4 bytes per pixel, its data will always be a multiple of 4.
However, the Alpha image might have some padding bytes to make its lines multiple of 4.

This means if the image width is a multiple of 4, like img2.png, your calculation is correct. For other images, the correct formula is:
Alpha bitmap data size = (image width rounded up to nearest multiple of 4) * (image height).

Right. Thanks for your answer. That's resolve my problem.