Using Channels

We can use the Channel panel in Photoshop to create Alpha Masks, a fundamental tool for manipulating images.

Using the Channels panel, we'll add a new channel (Alpha 1) with the button at the bottom right of the panel

Using the Gradient tool, set to Radial Gradient, with White as the foreground color and black as the background, we'll make a gradient that follows the bright spot on the original photo (in the upper right).

Once the gradient is made (seen here in red) we'll load it with the Load Selection button in the lower right of the panel.

This loads the gradient as a selection, with a very soft edge. Switch back to the RGB channel as the current channel, and turn off the visibility of the Alpha 1 channel, and turn on and make sure the new mason background texture is visible and selected in the Layers panel.

The marching ants you see show the 50% edge of the alpha channel. The area inside the selection will be affected by any actions we take in direct relationship to the grayscale value of the alpha channel we just created.

Choose Menu > Image > Adjustments... > Levels. Pull the white point handle on the histogram a bit to the left to lighten the selected region.

Choose Menu > Select > Inverse to select the opposite region.

Choose Menu > Image > Adjustments... > Levels. Pull the black point handle on the histogram a bit to the right to darken the selected region.

And now we have a fair facsimile of the mason board without the water spots and other details, but good enough to start working on the rest in a new layer.

Creating A Custom Brush for Spatters

Create A Brush Tip

There's lots of spatters on the mason board in the photo, so we'll make a custom brush along with a custom brush tip shape to get the effect we want.

Start by creating a new empty layer and drawing a brush tip shape with black (of varying opacity).

It should look something like this.
(zoom in to about 400%)

Then use the selection tool magic wand to select it.

Choose Menu > Edit > Define Brush Preset... to save the brush shape to use in another brush for making random spatters

Create A Spatter Brush

First, while still in the Brush tool, open the Brush Setting panel and choose the Brush Tip Shape tab. Using the brush tip we just made, set the size to 6 px, and the Spacing to 135% to get spatters that are not too close to each other.

Then set the Shape Dynamics to Size Jitter 50%, Control Off, Minimum Diameter to 50%, Angle Jitter to 100%, Contol off. This will create an individual spatter that changes slightly in size rotates at random.

Scattering will make the individual spatter dots spread out when you paint the brush. Set Scatter to the max value: 1000% and turn on the Both Axes checkbox.

Set the Transfer settings for Control: Pen Pressure for Opacity (not entirely clear in the UI that that's what it's for).

Save the brush preset by clicking on the New Brush button at the bottom right of the Brush Setting panel.

Name it something useful, like Spatterer

Put the brush into the Trompe L'oeil folder in the Brushes panel.

These custom brushes don't travel with the .psd file you're working on. You have to export them to make sure you have access to them the next time you're working in Photoshop.

Select the custom brushes with shift or control/command clicks, then choose Export Selected Brushes... from the popup menu in the upper right corner of the Brushes panel.

It's also a good idea to put brushes you commonly use into this folder, or even better, create re-save the brush (like Hard Round) and Turn on “Include Brush Settings” when you do, so you don't end up accidently using a regular Brush as a Mixer Brush.

Name it something useful and save the .abr file on a thumb drive to take with you.

To reload them, use Import Brushes in the same popup menu in the Brushes panel.

Painting and Blending

By and large, most of the work you'll be doing is with the General Brushes: Hard Round Brush, General Brushes: Soft Round Brush, and maybe Converted Legacy Tool Presets: Default Tool Presets: Cotton Blender*

The main trick is to change the brush size and opacity as needed, keep a copy of the source open and use the option/alt key to pick up colors.

* A word of caution about the Cotton Blender - it switches the Brush tool to a Mixer Brush, and doesn't switch back when you choose another brush. Remember to go to the Tool panel and reset the Mixer Brush to a regular Brush tool whenever you switch back to a different brush preset.

More Tricks

• Use layers with different blend modes and opacities
• Use Click - Shift - Click Again to draw straight lines
• Use [ and ] to change brush size
• Use < and > to change brush (another good reason to organize your brushes)
• User 1-0 to change brush opacity