3 y ago
Simple blendmode equations
| multiply | a * b |
| screen | 1 - (1 - a) * (1 - b) |
| darken | min(a, b) |
| lighten | max(a, b) |
| difference | abs(a - b) |
| negation | 1 - abs(1 - a - b) |
| exclusion | a + b - 2 * a * b |
| overlay | a < .5 ? (2 * a * b) : (1 - 2 * (1 - a) * (1 - b)) |
| hard light | b < .5 ? (2 * a * b) : (1 - 2 * (1 - a) * (1 - b)) |
| soft light | b < .5 ? (2 * a * b + a * a * (1 - 2 * b)) : (sqrt(a) * (2 * b - 1) + (2 * a) * (1 - b)) |
| dodge | a / (1 - b) |
| burn | 1 - (1 - a) / b |
http://www.blackpawn.com/blog/coding/2006/08/19/photoshop-blend-modes/
and http://www.pegtop.net/delphi/articles/blendmodes/
2 m ago
upgrade OpenSUSE from Leap to Tumbleweed
su
mkdir /etc/zypp/repos.d/old
mv /etc/zypp/repos.d/*.repo /etc/zypp/repos.d/old
zypper ar -f -c http://download.opensuse.org/tumbleweed/repo/oss repo-oss
zypper ar -f -c http://download.opensuse.org/tumbleweed/repo/non-oss repo-non-oss
zypper ar -f -c http://download.opensuse.org/tumbleweed/repo/debug repo-debug
zypper ar -f -c http://download.opensuse.org/update/tumbleweed/ repo-update
zypper dup