From 2a68848278acaea9189d72fab32ebcf06a065a3d Mon Sep 17 00:00:00 2001 From: Michales Michaloudes Date: Fri, 24 Dec 2010 10:12:58 -0200 Subject: graphics/gimp-wideangle-plugin: Added (distortion filter for gimp) Signed-off-by: Niels Horn --- graphics/gimp-wideangle-plugin/wideangle.html | 72 +++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 graphics/gimp-wideangle-plugin/wideangle.html (limited to 'graphics/gimp-wideangle-plugin/wideangle.html') diff --git a/graphics/gimp-wideangle-plugin/wideangle.html b/graphics/gimp-wideangle-plugin/wideangle.html new file mode 100644 index 0000000000..0e4682febf --- /dev/null +++ b/graphics/gimp-wideangle-plugin/wideangle.html @@ -0,0 +1,72 @@ +Gimp Wideangle Filter + +

Gimp Wideangle Filter

The Wideangle plugin is licensed under the GPL.
+The source code is available here. Latest version is +1.0.10.
+gimptool --install wideangle.c will compile the plugin and install +it in your local Gimp plugins directory.
+The plugin appears in the Filters/Distorts menu as +Wideangle....

The Wideangle filter is used to correct (or simulate) the distortion +typically seen on photographs taken with a wideangle lens. There are six +controls. +

X Shift: Adjusts the centre of the effect, from the left edge of the image (at -100.0), +through the centre (at 0.0), to the right edge (at 100.0).
Y Shift: Adjusts the centre of the effect, from the top edge of the image (at -100.0), +through the centre (at 0.0), to the bottom edge (at 100.0).
Main: Controls the amount of distortion. Negative values correct wideangle (barrel) +distortion, while positive values create it (or correct pincushion distortion).
Edge: Like the Main control, but the Edge control has more effect +at the edges of the image than at the centre.
Zoom: Zooms the entire image in or out.
Brighten: Adjusts the image brightness up or down with distance from the centre. +Can be used to remove (or create) vignetting, the darkening of the corners +of an image.

+ +

The Do Preview toggle enables and disables the preview window. +The preview can show either an overview of the whole image, or a detail view +which shows a 5x5 array of full resolution closeups. The overview is useful for +casual use, while the detail view +allows you to create a precisely calibrated preset for a particular lens. To create +a lens preset, use +a photo of a grid pattern. Start by adjusting the Main control until the +lines of the grid are as straight as possible. Use the Shift controls, if +necessary, to correct for any asymmetry. Finally, if the best setting of the +Main control leaves a "wiggle" in the lines, use the Edge +control to remove it. (You may need to readjust the Main control a little.) +Once you have the correct settings for a particular lens, you should be able +to save the settings as a new preset and use them for all images taken with that +lens.

+ +

Or just play around.

+ +

The preset controls allow you to reset everything, select a previously defined +preset, or save the current settings (if they've been altered) under a new name. +Preset names can contain (fairly) arbitrary characters. If you mess up the presets, +they are stored in a text file under your Gimp user +directory in the wideangle subdirectory.

+ +

Regardless of the Gimp's settings, the Wideangle filter always uses cubic +interpolation. This is not a bug, it's a feature.

+ +

What's with the pop up menu on the "select" button?

+ +

I originally had a regular option menu to select presets. However this had +a drawback, namely that the displayed option was only correct until a control +was adjusted. A pop up menu, although not the normal choice, provides exactly +the correct model to the user.

+ +

Written by David Hodson. Many thanks for suggestions and improvements +to Lars Clausen. (But bugs are still my fault.)

+ + -- cgit v1.2.3