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Let there be l… uhm… layers
Let there be l… uhm… layers
Published by Vlasta on October 14th 2008.
The development focus was on RealWorld Photos in the previous months and resulted in implementation of the “layers” feature, something that every serious photo editor should have, right? Maybe. Layers are a powerful, but controversial feature. They can help an application, but they can also harm an application if not handled with care.
Dark side of layers
Almost everyone knows about the pros of having layers, so let me say a few things against them:
- Layers add complexity. End users need to learn using layers, developers must implement them, application uses more resources.
- Layers are not needed for 95% of actions. Layers are not needed to resize photos, change file format, adjust colors, remove scratches, add watermarks, borders, etc. These are the only actions performed by a lot of users on photos.
- Layers are misused. Layers are powerful and people, who learn to use them, tend to overuse them. Often, a true vector editor is much better choice when creating computer graphics than a raster editor with layers. Layer with a rounded rectangle on it is not the same as a true vector rounded rectangle.
You got the idea… Due to the given facts, layer support will be optional and users can choose to turn it on or off in application options.
Layers in RealWorld Designer
RealWorld Designer is not an ordinary application as it is built upon a different set of values than other graphic applications. In case of layers, application of the power-design principle resulted in following properties:
- A layered image is a container for any number of images and combines them using given blending operation and layer opacity.
- Each layer must have RGB (and optionally alpha) channels. Layer can have arbitrary size and its position can be specified by user.
- Layers are by default simple raster images, but it is possible to use different kinds of images supported by the application. Layered image used as layer creates a tree-like layer structure. Rendered images can directly incorporate 3D models in RW Icon Editor.
- Effects can be applied on layers. An effect can be any operation available in the application (including sequence of operations, but excluding operations that resize the image). For example: drop shadow, glow, adjust colors, bevel, etc.
- Layers can have names.
Layers on user interface
Image filters work with currently selected layer. Layers can be easily added, removed, duplicated or re-ordered (using drag and drop).
The image above shows the look of the Layers panel. User can drag and drop image files on list of layers to add the images as new layers. Layered image can be flattened using a toolbar button. Individual layers can be deleted, duplicated, imported and exported and effects can be applied on layers.
User can configure whether to open images in standard formats (.jpg, .png, …) in layered mode or not. The lossless re-saving of modified .jpg pictures works with layered images just like with the non-layered ones and EXIF metadata are preserved.
The undo/redo functions work with layered images and more memory is reserved in layered mode for the undo buffer.
Summary
Layers were developed primarily for RealWorld Photos, where they are going to help to perform the more difficult retouching tasks. They will also find their place in RW Icon Editor or Cursor Editor and allow users to design icons more easily and adjust them later.
The current implementation of layers offers about a dozen of blending modes and supports layer effects. Layer effects is relatively scarce but useful feature in raster image editors allowing to apply effects on layers before they are composed. Photoshop allows a predefined set of effects and there is a plug-in for GIMP providing comparable functionality. In RealWorld Designer, layer effect can be any image filter. The most important of them were optimized to allow very fast interactive updating of the canvas while user draws into a layer.
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