I’ll explain how to do framebuffer screenshots on 16-bit and 32-bit framebuffer. For 16-bit this is fully based on http://docs.blackfin.uclinux.org/doku.php?id=framebuffer Capturing screenshots Whatever the bit-depth of your framebuffer, the first step is to capture the frambuffer raw data on the board:
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cat /dev/fb0 > screen.raw |
Now the you need to take the raw image, and convert it to a standard image format. This step depends on what type of display is there Converting 16-bit Framebuffer screenshot (RGB565) into png To convert the raw rgb data extracted from /dev/fb0, use iraw2png perl script
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#!/usr/bin/perl -w $w = shift || 240; $h = shift || 320; $pixels = $w * $h; open OUT, "|pnmtopng" or die "Can't pipe pnmtopng: $!\n"; printf OUT "P6%d %d\n255\n", $w, $h; while ((read STDIN, $raw, 2) and $pixels--) { $short = unpack('S', $raw); print OUT pack("C3", ($short & 0xf800) >> 8, ($short & 0x7e0) >> 3, ($short & 0x1f) << 3); } close OUT; |
To do the conversion, type the following command in the host:
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./iraw2png 640 480 < screen.raw > screen.png |
where 640 and 480 are respectively the width and height of your framebuffer. This has been tried on a 16-bit framebuffer on EM8620 series. Converting 32-bit Framebuffer screenshot (ARGB, RGBA, BGRA…) into png The solution proposed here is not as neat as the blackfin’s solution for 16-bit framebuffer, […]