Re: [Gimp-developer] history of "great" bugs

[yahvuu <yahvuu gmail com>]

Hello Saul,

Am 05.09.2012 20:37, schrieb Saul Goode:
> This brings us to the "overlay" mode, which most graphics programs define as using the "screen" mode when the upper layer is bright (above middle value) and "multiply" mode when it is dark.

just a nit to pick: it is the bottom layer which determines whether to perform screening or multiplying
 

> [..] My understanding is that GIMP implementation of "soft light" mode is similar to Borland's graphics library in their Delphi programming environment.
i presume you are referring to "Pegtop’s extensive survey of blend modes" [1].
The formula given there is exactly the GIMP implementation.

As you said, softlight can be regarded as a smoothened variant of overlay mode which offers softer transitions.
Mathematically, this formula describes a linear cross-fade between multiply and screen depending on the base layer value.



best regards,
yahvuu


[1] http://www.pegtop.net/delphi/articles/blendmodes/softlight.htm