Legacy ImageMagick Discussions Archive

Alright, thank you.

I 'm not really familiar with command style in IM, is there a reason why explicit is not going to work?

This image seem to have monochrome alpha (either 0 or 255) but is fine otherwise.

I admit that it is not fully supported and some applications tend to ignore saved alpha, but it works good as a resource file.

BMP3 which is BITMAPFILEHEADER + BITMAPINFOHEADER can hold alpha channel, biBitCount need to be 32 and biCompression BI_RGB as stated here.

MSDN page states that

Alpha values per pixel are only supported for 32-bpp BI_RGB.

Anyway, v3 bitmaps with alpha are used everywhere.

It seems to be a bug since imagemagick correctly saves alpha in BMP4 while BMP3 definitely does allow transparency or at least 32 bpp (exactly as BMP4). And it is actually stated later on that page: For comparison, the bmp3: format allows bit depths of 0, 1, 4, 8 ,16, 24 and 32 and has extra fields ...

fmw42 wrote:For your output use BMP3:output.bmp

this approach gives me exactly the same bitmap as -define bmp:format=bmp3

I'm trying to convert pngs into bitmaps with premultiplied alpha to be used as Portable Executable resources with Power Shell script: $converter = "`"C:\Program Files\Image Magick\convert.exe`"" foreach($file_path in $args) { $file_name = $file_path.substring(0, ($file_path.length - 4)) $command ...