I like using the iPad for decision making when I get stuck on where to go next in the painting process in acrylic painting. This technique can be used for any art medium. I I use either the ArtRage or Procreate apps. In this tutorial, I am using ArtRage.
To get the painting into the iPad, I take a photo with my iPhone or iPad of the painting trying to get close enough so the painting covers as much of the painting as possible.
I open a new painting in the ArtRage iPad app. Below is a screenshot of the ArtRage interface with a new blank painting. As you are working, the row of tools and the color picker will disappear when you click on the active tool and color giving you more canvas to view and work with.
Then I import the photo of the painting into ArtRage. Click on the second to right bottom icon to import the photo. It comes into the program as a tracing image at 40% opacity. To see the painting at full opacity, click on "Convert to Paint" under tracing options. Tracing options is the third icon from top in the same bottom icon. It looks like three horizontal lines one below the other.
Then click on the eye icon , and the painting will show at full opacity.
I add a new layer above the painting so I am not working directly on the painting. The fourth icon fron the right on the bottom of the ArtRage interface is the layers icon. I paint on new layers, keeping objects and new painted effects on separate layers. This way I can turn on or off the visibility for each layer to see what I like or don't like.
I generally use the watercolor or oil brushes, but may also use crayons and color pencils. Each brush has several settings for different paint looks. You can change size and properties of each brush by clicking the two left bottom icons. Both control different brush properties.
For this painting, I was unsure if I wanted to add a planter and flowers. I added a planter on the floor. Then I added flowers and a plant -- all on separate layers. I turned on and off the visibility on the various layers and saved versions or took screen shots of the various versions. Although the added objects will not look the same when added to the painting, they are similar enough to help me decide if I think they will be good additions.
Here is the finished painting. You can see that I did add the planter, but not the flowers and plant. I also experimented with adding layers of color to certain areas and did so on the painting itself.