How to use color channels with Affinity Photo filters such as equations and mirror filters tutorial
Open a document in Affinity Photo and then go to the channel panel (view menu and studio and channels if it is not available).
Once you have the color channel panel displayed you will notice a number of panel entries such as composite red, composite green and composite blue, composite alpha and a number of others depending on the document and other channels you have created either based on those channels etc. This also depends on the color / image model for the document so the list will be different if you are using CMYK or LAB
You can right click context menu on any of the panels in the channels, to display commands such as
1) load to pixel selection
2) subtract from pixel selection
3) create spare channel etc
To select a channel
1) just select the red etc channel and then you will see the pixels in the red channel only in the document (you will notice all the other channels are disabled / hidden etc)
2) Select the composite green etc (or cyan etc)
3) Select the blue channel
To reset back to all the channels, click the little circular reset at the top of the panel to bring them all back online.
You can use the filters in the red channel as well as the green etc independently.
I have yet to use a filter that doesn't allow for this but they may exist for other modes as sometimes certain filters just can't be used with a single channel (certainly the case in some applications).
1) Go to the channel panel
2) Select red channel
3) So now, go to the filters menu and distort and equations (you could equally use blur or radial blur or some other filter) and then you will see the equations filter editor panel. Using the default coordinate system and set extend mode to wrap and the x= to x+500 etc (half of the current size of the document, I don't know if there is an equations constant for the document width) and then you will see the image shift in the red channel only half way and wrap half way. Click apply.
4) Now select the composite green in the channel panel
5) go to the filters menu and distort and equations and instead of using x+500 etc, set the y= value and set to y+500 etc (depending on the height of the document and half of that). Again, select wrap and then click apply
6) Go to the composite blue
7) filters and distort and equations and now click the polar option and wrap and set the r= to r+200
8) Now you have edited all the channels independently, click the little circular icon at the top of the channels panel or go through all the channels and click the visible and editable icons and you should see an unusually colorful shifted design (but still recognisable as the image)
You can also then apply filters to the entire image instead of the individual channels. You can then go back to the individual channels and use different filters such as gaussian blur etc
Many of the plugins available on this site such as the Andrew's Plugins for Photoshop PC / windows 180 amazing effects such as blurs and patterns etc can also use the color channels in an independent manner as can the resources such as brushes such as plus and abstract cross brushes and super spotty polka dot brushes
You can also use color channels panel and layers in Affinity Photo to create some interesting effects, combining those layers with blending modes.
1) Select an image
2) Go to the layers panel
3) Layer menu and duplicate
4) Layers menu and duplicate
You should now have three layers all with the same image
5) Uncheck (hide) the first two top layers via the layer panel
6) Go to the visible layer
7) Go to the channel panel and select the red channel
8) Apply an effect such as radial blur
9) Go to the channels panel and select the green channel
10) Now check the middle layer in the layer panel and use that layer
11) Apply effect with different settings
12) Go to the channels panel and blue
13) Select and check (make visible) the top layer
14) Apply effect
15) Go to channel and click the reset at the top of the panel to display RGB
16) Go to each of the layers in the layer panel and set the blending modes accordingly such as difference or overlay
You should then see the effects applied to the red and green and blue channels and also the result of the blending modes applied to the layers
You can find many more tutorials on the site such as how to use the equations filter in Affinity Photo and example code and how to use Affinity Photo extensions in Apple Photo on the latest Mac OS and how to use snapshots in Affinity Photo to capture your work and How to use the Bilateral blur in Affinity Photo for stunning visual blurring and sharpening effects and how to use the mininum blur filter for dark image effects in Affinity Photo and how to use the affine filter in Affinity Photo tutorial to create interesting transformations and rotation