The topic for discussion was the interactions between Selections, Masks, Channels and Paths (and layers).
An introductory demonstration was given to show that a Selection can be readily turned into a Mask by using the Photoshop Quick Mask (Q) which can be used to make detailed adjustments before returning to the Selection.
Selections can have either hard or feathered edges. A selection with a feathered edge of, say 10 pixels will fade from 100% 10 pixels inside the selection to zero 10 pixels outside the original hard selection.
Photoshop shows selections with 'marching ants' along the 50%
selection line.
A Selection can be saved in the file (Select | Save Selection), the
default name is Alpha 1, as a Channel and the selection can be
regenerated by Ctrl + Clicking on the icon of the channel. Any
feathering is preserved in the exchange between Selection and Channel.
A Selection can also be saved in a new document from the Select | Save
Selection dialog box.
A Selection can also be saved as a Work Path by going to the Paths
palette and clicking on the fourth icon from the left at the bottom of
the palette. The Work Path is transient but can be made permanent by
renaming.
The third icon from the left on the bottom of the Paths palette will
convert the Path back to a Selection. However, this will demonstrate
that converting a feathered Selection to a Path loses the feathering.
This is because of the nature of paths which are lines representations
of a mathematical formula. Zooming in on a path will show that it is always a line whereas zooming in on the edge of a selection will, eventually, show that it is pixellated.
The conclusion is that a Selection can be turned into a Channel, which
is a mask, which is a type of layer and back again; whilst a selection
can be turned into a path, which is a different type of layer, and
back again, any feathering is lost in the process.
Two short exercises were presented for members to explore the uses of selections and paths and the ability to change between them.
Convert Selection to a Channel to a Path to a Selection
Open the Dune.jpg file.
Rename the layer 'dune: double click on the text of the name Background 'dune'.
Create a new layer below the dune layer: Ctrl + Alt and click on the new layer icon.
Name the new layer 'white'.
Fill it with white: make sure the default colours are set (D) and then Ctrl + Backspace. This is just to enable you to see what is going on a bit better.
Draw some guides to define a rectangle roughly in the middle of the screen.
Make sure Snap is on: View | Snap
Select the Rectangular Marquee tool (M), make sure the Feather in the Tool Options bar is set to zero and draw a selection in the rectangle defined by the guides.
Make sure the dune layer is active then Ctrl + C followed by Ctrl + V to paste the selection to a new layer.
Hide the dune layer. The new layer contains a sharp edged rectangle picture from the layer below it. Hide this new layer and make the dune layer active again.
Change the Feather value to 50, deselect (ctrl + D) and then re-draw the selection in the rectangle. Again, cut and paste the selection and hide the dune layer. The new selection is feathered or softened inwards and outwards.
Save this selection: Select | Reselect then: Select | Save Selection, and accept the defaults. Then de-select (Ctrl + D).
Now go to the Channels palette, click on the bottom one called Alpha 1 and hide the others. This Alpha 1 Channel is a mask – as are all channels.
Make sure the default colours are set (D)
Select the Eraser and draw a couple of lines across the Alpha 1 channel; flip the colours (X) and draw another couple of lines.
Un-hide all the other channels just to check what is going on and select the RGB channel.
Hide the Alpha 1 channel.
Go to the Layers palette, Select | Load selection, choose the Alpha 1 channel and press the delete key.
So, a Selection converts easily to a Channel which is in fact a Mask.
Ctrl click on the Alpha 1 icon we have a new Selection.
And a Channel converts to a Selection.
Now go to the Paths palette and look at the icons along the bottom, click on the one in the middle which looks like an O with a bit of string draped across it. This converts the selection to a Work Path, which is transient so rename it to 'selection'.
Ctrl + click on the path's icon and it is converted to a selection again.
Go back to the layers palette and make sure the dune layer is visible and active.
Press the Delete key (if you have already done this then first you need to restore the image to what it was before you deleted it last time).
To restore the image, go to the History palette and find the layer named Clear, click in the box on the left hand side of the line above this to mark this as the place to get information for the History brush (Y) which you use next to paint back what you deleted before.
Press the Delete key again.
A Selection converts to a Path, and back again but …
This time the edges of the selection are all sharp again and it includes all those pixels that were at least 50% selected before.
Channels and Paths can be created from Selections which are saved with the file in Photoshop format and used again in the future (and can be dragged to other files as well) but there is a restriction that Paths always have sharp edges whereas Channels and Selections can have soft
or feathered edges.
Torn edged Text by courtesy of Photoshop User TV (182) and
blog.spoongraphics.co.uk.
Open a picture e.g. Dune.jpg.
Add a text layer: Select the Type tool and type 'I tore this out'. Use black Arial bold about 75 pt.
Draw a rough selection round the text with the freehand lasso tool.
Add a new layer below the type layer, fill this with a near white
colour.
In the Paths Palette menu, create a Work Path with a tolerance of 1.
Select the Brush tool; Select the 14 point spatter brush, just below the Airbrush soft round
about halfway down the standard brush list.
Click on the Brush presets tab at the right of the Tool Options bar. Select Shape Dynamics and Scattering and change the Size Jitter & Angle Jitter to 100% and the Scattering to 50%.
Stroke the path with the brush using the same colour as previously, second icon from the left of the Paths palette.
Clear the path by clicking below the Work Path layer.
Select both the Text layer and the Paper layer, link them by clicking on the first icon on the left of the Layers palette.
Rotate the layers. Edit | Transform |Rotate.
Unlink the two layers.
Open the crumpledPaper.jpg, select all and copy this to the clipboard.
Back to the Dunes.jpg: Make sure the Paper layer is active. Ctrl click on the paper layer to get a selection and then Edit | Paste Into; and then change the Blending mode of this layer to Overlay.
This gives a crumpled effect to the torn piece without adding any colour.
Hide the Paper layer; make a selection from it by Ctrl clicking on its icon.
Make the Background layer active.
Edit | Copy, Edit | Paste to add a new layer with the selection. Move this to just above the Paper layer. Rename this layer Selection
Add a drop shadow to the Selection layer with the default settings: double click on the layer to the right of the layer's name and choose Drop shadow.
Right click on the Drop shadow effect and select Create Layer from the pop up menu (3rd from bottom).
Edit | Transform | Warp and twist the drop shadow layer.
Magazine Cover by courtesy of Photoshop User TV (181)
Select a picture such as the chinese child.jpg where the background is irrelevant.
Use the Magnetic Lasso tool (L) to select the child and its toy, jumping into Quick Mask (Q) to do the final adjustments.
Feather the edges by about 2 pixels and then invert it.
Save the selection. This converts the Selection to a Channel – which is saved with the file.
Select the Linear Gradient tool (G) and the Foreground to Transparent gradient.
Create a new layer and label it Gradients.
Drag down from the top down to the child's feet and then up from the bottom to its knees. This will remove unwanted background images and present a suitable background for the magazine's title.
Add some white text 'The Chinese Toy Magazine May 2009' putting the word Toy on a line by itself.
Change the font of 'May 2009' to about 6 pt and the rest to about 16 pt. This should get all the text across the picture.
Use the Move tool to position it at the top of the picture – but this puts text in front of the child's chest.
Ctrl + click on the icon of the Alpha 1 Channel to create a selection
With the Text layer active, click on the third icon from the left on the Layers palette – Add a Layer Mask.
This will hide the text in front of the child.
_ - o O o - _
The next meeting, on June 17 will re-visit this topic.
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