SUMMARY

Selections

  1. A selection is a window to the underlying pixels of the active layer. It is helpful to think of the selection as areas where there are "holes" in a transparent mask where the canvas can be drawn on or modified.
  2. Only pixels within the selected area can be modified with other actions(e.g., filling with a color or pattern, adding a stroke, or transformation). Everything else in the image will be considered protected from modification.
  3. You can also think of a selection as a stencil or a masking tape that protect or expose paint on the surface of another object (e.g., poster, wall).
  4. You typically "know" you have a SELECTION (with one major EXCEPTION) by viewing the marquee which is commonly known as the "marching ants" on the canvas. This is an EXPLICIT (clearly seen) selection.
  5. If you don’t have anything selected, you will have an IMPLIED (suggested without being directly) selection of the whole canvas without any marching ants.  If you don't have anything selected, the whole canvas is a SELECTION.
  6. If you want to “see” the selection of the whole canvas, press Select > All or CTRL + A to select all of the pixels on the canvas with the marching ants showing around the whole canvas. This is NOT necessary unless you want to copy or cut the whole image to another file.
  7. Look behind the curtain to see what is certain. If you want to "see" what is actually selected or not selected, turn on the Quick Mask (Q key). Typically, you will see a red translucent Quick Mask with areas that have "holes" (clear areas) cut out of them. These holes or clear areas represent the actual selection once you exit the Quick Mask mode by clicking on the Q key again.
  8. It is important to note that you can not view the selection AND the Quick Mask at the same time. To bring back the selection, you have to exit the Quick Mask mode (e.g., pressing Q key again).
  9. The Quick Mask is red by default, however, if the image contains a lot of red color in it, you may want to change the Quick Mask overlay color to a different color by double-clicking on the Quick Mask icon and then clicking on the Color chip to change its color
  10. Because a selection behaves like an transparent mask with holes in it, only what's selected gets affected by what you do next (e.g., cut, copy, transform, etc.). Hence, a selection provides "protection" for the unselected pixels. If you make a selection and then decided to cut or delete the selected area, only the area where the selection has been made will be affected.
  11. If you don't have anything selected, the whole canvas is affected by what you do next.
  12. It is important to note that while only what is selected get affected, it is more important to not that the layer that is selected is the layer that get affected. Ensure you are on the right layer before you do something after creating a selection.
  13. To learn more about the various ways to create selections, see the app called "Learning Selections From The Joes."

Layers

  1. A layer is similar to acetate sheet (clear plastic film) stacked on top of one another so that:

    • The underlying pixels of each non-overlapping pixels show though to the top most layer
    • The underlying pixels of several layers may be blended together creating a unique "blend" of all associated pixels
  2. A layer can be thought of as a mask because it can show, hide or protect pixels underneath it.
  3. It is important to note that the transparent areas of a layer will still protect layers below it. It is helpful to think of the transparent areas as a "clear glass." Even though you can "paint" on the clear glass, it will still protect the underlying layers from getting painted on. Only the layer that was painted on will get affected by the paint.
  4. Similar to layer's transparent areas, a layer's opacity can make a layer behave like a mask (e.g., shows hides, or protects). The difference between the two is that a layer's opacity affects the whole layer not just the transparent areas of the layer.
  5. A layer's stacking order can also play a role in making a layer behave like a mask because it can help to show or hide the underlying pixels on a layer below it. If the top layer has neither transparency or opacity, then it will be the only visible layer. To see another layer, it would have to be moved above the top layer.
  6. Lastly, a layer's Blend Mode setting in the Layers panel can also make a layer behave like a mask. The blend mode setting will determine how a layer's pixel will "blend" or interact with other pixels below it. There are a host of blend modes (e.g., Normal, Dissolve, Hard Light) available that you can experiment with to "see" the affect of the blending.
  7. The Normal blend mode causes layers to behave as the name implies "normally" without any "blending" of pixels. Hence, the normal mode is NO blend setting at all.
  8. To learn more about the various ways to create layers, see the app called "Learning Layers From The Joes." In the app, you will learn how to create the following types of layers: regular, custom shape, adjustment, smart object, 3D and text.

Masks

  1. Black conceals, white reveals.
  2. Layer mask / Alpha channel – black hides pixels, making areas on the image transparent. White shows pixels to reveal areas of the image.
  3. Gray conceals and reveals pixels making them translucent.
  4. Gradient mask – different shades of gray will show different degrees of transparency.
  5. Quick mask – red conceals the selection, clear reveals the selection.

There are various types of masks; however, they all do the SAME things but in a DIFFERENT way.

All masks:

  1. can be seen by one or more means (e.g., Quick Mask, thumbnail, clipping icon).
  2. can be created and then modified by one or more means (e.g., Add Layer/Vector Mask, painting or erasing).
  3. are based on other objects (e.g., selection, bitmap, vector).
  4. can show, hide or protect pixels of an underlying layer(s) (e.g., black conceals and white reveals).
  5. can show various degree of transparency (e.g., gray will show as a translucent color).
  6. are store somewhere (e.g., Layers/Channels, Path panels).
  7. can create a selection (e.g., CTRL + click on a mask's thumbnail or layer with transparency, turn off Quick Mask).
  8. can assist with creating non-destructive editing (e.g., selections, layers, and masks).

Once you realize the above concepts, it will help to "take" the mystery out of creating and modifying any mask.

Mask definitions and where they can be seen:

  1. Quick Mask – a bitmap mask based on a TEMPORARY SELECTION.
    It can be seen:
    1. In the Channels panel as a small black, white or gray thumbnail mask with the word "Quick Mask" next to it.
    2. On the canvas as a red translucent overlay mask with clear areas ("holes") or as a selection when the Quick Mask is turned off.
      NOTE: It is a temporary mask because once you exit the Quick Mask mode the thumbnail mask goes away in the Channels panel.

  2. Alpha Channel Mask – a bitmap mask based on a SAVED SELECTION.
    It can be seen:
    1. In the Channels panel as a small black, white or gray thumbnail mask.
    2. On the canvas as a selection if you CTRL + click the Alpha Channels thumbnail mask.
      NOTE: It is a permanent mask because once you save a selection it stays in the Channels panel until you delete it.

  3. Vector Mask – a non-bitmap (vector) mask typically based on an EXISTING PATH.
    It can seen:
    1. In the Layers panel as a small white or gray thumbnail mask next to the actual image thumbnail.
      NOTE:       There is no black area in a Vector Mask.
    2. On the canvas where gray areas of the thumbnail mask will conceal pixels (make areas of the image transparent on the canvas) and white areas of the thumbnails will reveals pixels (make areas of the image visible on the canvas).

  4. Layer Mask – a bitmap mask typically based on an EXISTING SELECTION.
    It can seen:
    1. In the Layers panel as a small black, white or gray thumbnail mask next to the actual image thumbnail.
    2. On the canvas where black areas of the thumbnail mask will conceal pixels (make areas of the image transparent on the canvas) and white areas of the thumbnails will reveals pixels (make areas of the image visible on the canvas) and gray areas of the thumbnail mask will make translucent pixels (make areas of the image show various degrees of transparency).

  5. Gradient Mask – a bitmap mask based on a GRADIENT applied to a Layer Mask.
    It can seen:
    1. In the Layers panel as a small black, white or gray gradient thumbnail mask next to the actual image thumbnail.
    2. On the canvas where black areas of the thumbnail mask will conceal pixels (make areas of the image transparent on the canvas) and white areas of the thumbnails will reveals pixels (make areas of the image visible on the canvas) and gray areas of the thumbnail mask will make translucent pixels (make areas of the image show various degrees of transparency).

  6. Clipping Mask – a bitmap or vector mask based on a BITMAP IMAGE or a VECTOR SHAPE.
    It can seen:
    1. In the Layers panel as a bitmap image or vector shape layer that acts as a mask for one or more images ABOVE it.
    2. On the canvas as the bitmap image or vector shape it is "clipped" into.
  7. Filter Mask – a bitmap mask based on a FILTER EFFECT applied to a Smart Object.
    It can seen:
    1. In the Layers panel as a small black, white or gray thumbnail mask BELOW a filter effect that is applied directly to the actual image thumbnail.
    2. On the canvas where black areas of the thumbnail mask will conceal pixels (make areas of the image transparent on the canvas) and white areas of the thumbnails will reveals pixels (make areas of the image visible on the canvas) and gray areas of the thumbnail mask will make translucent pixels (make areas of the image show various degrees of transparency).

  8. Adjustment Layer Mask – a bitmap mask based on an ADJUSTMENT LAYER PROPERTY.
    It can seen:
    1. In the Layers panel as a small black, white or gray thumbnail mask on a special adjustment layer ABOVE the layer(s) that it is "adjusting."
    2. On the canvas where black areas of the thumbnail mask will conceal pixels (make areas of the image transparent on the canvas) and white areas of the thumbnails will reveals pixels (make areas of the image visible on the canvas) and gray areas of the thumbnail mask will make translucent pixels (make areas of the image show various degrees of transparency).