Chasys Draw IES Help:

Introduction to Layers

What is a Layer?

Layers can be thought of as transparent sheets of transparent plastic with images drawn on them, that can be stacked on top of each other, so that you can see the lower sheets through the transparent parts of the upper sheets. Layers allow an artist to produce his work in pieces that he can move and edit independently.

The illustration above shows the concept. The image on the right is made up of the three layers on the left: one with the background at the bottom, followed by one with the portrait, and finally, one with the text at the top. Layers make it very easy to create relatively complex imagery. An additional advantage is that they also make it easier to re-edit saved work, as the layer that needs adjustment may be removed and edited separately.


What is a Free-style Layer?

A free-style layer is one that can be positioned anywhere, including totally removing it from the image and keeping it aside; in which case it remains visible and fully accessible.

Chasys Draw IES Artist provides free-style layering to make it possible for you to work with images the same way they would if the images were photos placed on your desk - you may stack what you need together, while placing pieces that you are not currently using outside the stack but within reach.

The concept of free-style layers might be a bit confusing to users who have been working with other editors (and are therefore not used to being able to see off-screen layers), but I believe that it enhances productivity for existing users and improve the learning curve for those who are new to image editing. Free-style layers allow you to work the way you want; to work efficiently and freely, and by your own terms.

To make things easier for you, Chasys Draw IES has an image mode that simulates the behaviour of traditional image editors, namely Composite / Clipped. In this mode, layers (or parts thereof) that are outside the canvas are partially clipped to give a user experience that is similar to the aforementioned traditional editors.

Layer Attributes

Layers have attributes that determine their behavior. The most basic is the position, which just sets the layer's position relative to the first layer. The z-order determines which layer is on top of which one. The layer with the highest z-order is placed on top of the stack, and the one with the lowest z-order is placed at the bottom and treated as the background. Layers can be prevented from moving (relative to the background) by applying the locked attribute, and they can be made invisible by applying the hidden attribute. Layers can also be excluded from the final work without making them transparent, this is done using the excluded attribute. The transparency attribute sets the global alpha for the layer; per-pixel transparency values are blended with the global alpha when the layer is being rendered.

Shown on the left above above is the layers window, which shows you the list of layers that make up the image you are working on. Right-click the list to bring up the options for the layer. Double-click or select the properties entry to bring up the layer properties dialog shown on the right. The layer properties is a floating toolbar just like the layers window; you can keep it open as you work and it will automatically track any changes you make.

The table below lists the common layer options and what they mean:

Option Meaning
Hidden Layer will not be displayed at all.
Locked Layer cannot be moved using the Hand Tool.
Excluded Layer will not be printed or included in flattened/final representations of the image, but will remain visible in the editor.
Alpha Protected No tool will be allowed to change the transparency of any pixel in the layer; only the color can be changed. As a result, the alpha channel is preserved, or "protected".
Click-Thru Layer cannot be clicked on. Any clicks will propagate to the layers below it.
Floating Layer will always be displayed above all non-floating layers, irrespective of z-order.

The layer menu can also be brought up by right-clicking the actual layer with the hand tool within the main window. Selecting the properties entry in the menu brings up a dialog box where you can set all layer attributes.


Image Modes and Blend Modes

The rendering (drawing) of layers in Chasys Draw IES Artist is dictated by two parameters, the image-mode and the blending-mode.

The image mode, which is a concept that is unique the Chasys Draw IES, dictates how it interprets the layers; for example, in the “frame animation” image mode, layers are interpreted as video frames and in the “image-list” image mode, they are interpreted and separate pages or copies with different resolutions. Some layer attributes may be unavailable when using certain image modes. This is by design; not all attributes make sense in all image modes.

The blending mode determines how the layers interact with each other when using one of the “composite” or “object animation” image modes. Blending modes are not unique to Chasys Draw IES; many other image editors has a similar concept. Chasys Draw IES supports more than 20 blending modes, including a custom mode that allows the definition of new blending mode and/or the importation of blending modes from other image editors. Chasys Draw IES comes pre-packaged with some unique blending modes from Photoshop, GIMP and Paint.NET.


Adjustment Layers

An adjustment layer is a special layer used to perform non-destructive editing by applying adjustments to your image without permanently changing pixel values. For example, rather than making a Curves adjustment directly to an image, you can create an adjustment layer and make the Curves adjustment to that instead. The adjustments are stored in the adjustment layer and apply to all the layers below it; you can correct multiple layers by making a single adjustment, rather than adjusting each layer separately. You can change or discard the adjustments at any time.

One adjustment layer can have multiple adjustments in it. This is a feature unique to Chasys Draw IES that is intended to improve final image quality.


What are layer attachments (metadata)?

Chasys Draw IES can add descriptive information, such as the name and style of font used, path data, etc. to a layer. This information is called metadata, and is saved along with the layer as an "attachment", much like the attachments you use with e-mail. If the layer were to be opened for editing later, this information will be restored and may be use to aid the editing process.

Attachments can be in various formats; each format is identified by a four letter code, e.g. PATH or NOTE. The four letter code is case sensitive, but you don't need to worry about this because it's handled internally.

Each layer can have several attachments. Most are added automatically by the tools you use, for example, the Pen and Path tool uses PATH, while the Text tool adds TEXT. Some are used by objects and plug-ins, for instance, the MARK (mark-up) attachment is used by the brush object to store brush attributes and by the cursor load/save modules store hotspot and color-depth information, while BLND is added by the Photoshop PSD file plug-in to add support for Photoshop-specific blending modes.


What is a mark-up attachment?

Sometimes, it is necessary to pass application-specific information about a layer, such as the cursor hotspot, to an external module, such as a file format plug-in. Because such information is not part of the standard layer attributes, it must be specified differently. One of the ways of doing this is using a mark-up attachment (type MARK), a list of variables in plain text. An example of this is the image.bpp tag used to indicate that a layer's preferred bit-depth; setting this to 8 will cause the layer to be re-sampled to 256 colors by a plug-in that supports that function. A typical mark-up would look like this:


When saved as a cursor, this instructs the cursor module to assign a hotspot at (x=12,y=15) and store as a full-color image with a full alpha channel (Vista-style cursors and icons).

Mark-ups can be added and removed using the Mark-up dialog-box. For a more in-depth discussion of MARK, see the article on Mark-up Attachments.



Copyright © John Paul Chacha, 2001-2019