Pixelated

Oh! Much better.  So just for everyone else out there, just do steps 1, 2, and then hit delete to make the sampled color become transparent.
 
Thank you!

Callum,
Thank you for this procedure, but it no longer appears to work in the current version of the Affinity Photo software.  I just tried it and I could do all the steps except for step 6.  When you right click on the spare channel that you just created, there is no option to "Load to Background Alpha".  Instead there are the options to "Rename", "Delete", "Load to Pixel Selection", "Add to Pixel Selection", "Subtract from Pixel Selection", and "Intersect with Pixel Selection", none of which seems like the correct option for this task.  
For reference, I'm using Affinity Photo v1.6.11.  Not sure when the change occurred, but unfortunately this solution no longer seems to work. Any other suggestions from anyone out there?

Hi Folks
 
Is there a way in either Photo or Designer to convert a solid colour in an existing image (let's say a png for the sake of argument) and make it transparent?
 
I've found many existing posts about transparency. Some relate to creating an image with a transparent background which isn't applicable here. Some relate to existing images but I don't believe it's quite the same scenario; nothing I can get to work anyway.
 
So effectively I'm looking for the equivalent of GIMP's 'Color to Alpha' function. I've had to install GIMP just for this purpose; I'm struggling to believe there isn't a way of doing it in either AD or AP but I'm not that au fait with image programs of this complexity.
 
Thanks
 

You could add a new Pixel layer above the source image, set that new layer's blend mode to Colour, and then use the regular Paint Brush Tool to paint into that.

Literally the first thing I tried doing with affinity photo. 
Developers please make this available ASAP, this is pretty much THE tool I use in photoshop, it shouldn't take more than a couple steps. its simple stuff, kind of a deal breaker for me. 

R C-R, I agree that my example looks somewhat unnatural, but I didn't play around with it to get it to look more natural and I didn't try to refine the edges. I was just doing a quick example to show how the replace color feature works. The above example literally took me about a minute to do. I would think if Affinity Photo had a similar tool for replacing color that it would also have more options for fine-tuning.

Just thought I'd chime in: I'm not a professional and I've never used Photoshop. I just like playing around with image-editing software. I already owned Affinity Designer and Affinity Publisher, but I bought Affinity Photo this weekend because it was 50% off. I've fiddled around with it and watched a lot of tutorial videos and the program seems fantastic. However, I also own Pixelmator Pro, which I bought over a year ago. I haven't used it a lot and it definitely now feels limited compared to Affinity Photo, especially because Pixelmator Pro doesn't have anything similar to Affinity Photo's adjustment-layer masking. However, Pixelmator Pro has a really simple Replace Color feature that works well. You first choose the color you want replaced from the color picker or by clicking on a color in the image. Then you do the same for the color you want as the replacement.
I've attached two screenshots.The woman's sweater was originally red, but I changed it to the color of the blue rectangle.

@HarryMcGovern yes, that would be nice. In case, for whatever reason, let's say you can't have #FF0000 anywhere in your image and rather than hunting down those pixels, you can just swap them to one off.

Hi I just want to state that while the color replacement brush works fine when one doesn't want to mask and recolor certain parts, I would still very much like to have just an easy way to say take this rgb / hex value and make it this other one everywhere. Please make this a feature.

Hi Pixelated,
Welcome to the forums
Please could you try (With the Node Tool Selected) Hold right click away from the Node you want to convert (Your right click menu may appear just ignore it). Then with Right click still held left click the node you would like to convert into a sharp node. You can also do this while holding CTRL with the Pen Tool as that switches it to the Node Tool.
Thanks
Callum

The same way, you can use the flood select tool, the selection brush, any of the marquee tools including the freehand tool of which there are the subsets of freehand, polygon and magnetic.
Make sure the layer you are selecting from is a (Pixel) layer not an (Image) layer, to make an (image ) layer a (Pixel) layer just right-click and select Rasterise. 
Go to Select > Grow shrink

So still nothing on this? Honestly is very much pain in the b*** to select circles. And having to construct a shape to ctrl select it is just slow. Also not to mention that rasterisation of layers is annoying, why isn't there a default shortcut for it if it is important option?

Same same...please, can someone give us an ETA? It's 2020, it was first queried (above) in 2015. It's maybe ohhh 25 years since it was do-able in other software. I love Affinity products soooo much, but can't understand this function being missing.

It's now January 2018 and the issue is still not resolved. As somebody who's profession is designing mandalas (something that requires symmetry as well as expanding from the *center*), it's a little disappointing that something so basic has still not been added. I purchased the Affinity suite the minute they released on the mac app store, and again on all my windows machines. It has replaced the adobe suite for me, but this feature has always annoyed me.
 
My workaround so far has been to create vector shapes (since for some reason they're allowed to created by expanding from the center?). It honestly confuses me why at the very least the tools aren't consistent. Why does the ctrl/command key perform differently on the shape vs marquee tool when they are essentially doing identical things?
 
I really hope they see this thread and start considering adding it. I can't see why from a programming standpoint it would be difficult to add, since the functionality is already existent in the app.

02 July 2017: They just don't solve this. Why make such a simple operation complex?

The original post referred to expanding from the center.  That is still not available in RC2.  (Or if it is, I haven't discovered how to do it.)  And it is still greatly desired.  I don't know why such a basic option has been ignored for so long.

About 18 months have elapsed since your post and this issue is still unsolved.
Tips, Tricks and Workaround are not the solution.
I do not understand why they refuse to accept the matter of fact that, as they are at the present, the Marquee Tools are hopless and useless.
I hate functions that make complicate the easy matters.

Good workaround, Scott, but you can do it even quicker by just Command-Click the shape layer and then delete the layer (you don't need to choose Layer to Selection). Soon you do it almost as fast as in Photoshop.
 
But I do agree, give us the Command-Drag feature here too, Affinity!

Found a workaround for now: 
1. Draw a new shape in expand-from-center mode (Commad-Drag)
2. Choose "Layer to Selection" (Shift-Command-O)
3. Press the delete key to delete the layer with the shape on it
4. You're left with the selection you wanted!
 
A few extra keystrokes, but it gets the job done.  
 
 
Just Command-Drag for Marquee creation would a nice feature, and consistent with other tool behavior!

In the dropdown menu for text styles there is an option to Import styles.  However there doesn't appear to be an option to Export them. I created my own styles in a document and would like to bring them into a new document. Is there a way to do that? The import would look to export the whole set rather than selective so presumably the export would be as well.

The thing is, Designer is a page layout program, like MS Word or Quark. You create a page first and place objects on it, often with bleed and maybe crop marks, etc.
So what you are trying to do is resize the page to fit a single component on the page. It is possible by creating an Artboard but it will be a bit of a workaround.
Still, try fitting a page to an object in either MS Word or Quark 
This is what image editing programs like Photo are designed for. They are based on a canvas, not a page, so they work very differently. 
Another way around is to copy the item, then go File > New from Clipboard. That might help ?

thanks imfastrnu2
 
That's true, but here at work most of my export have to be in PNG so this feature would be most appreciated.
It's really annoying having to create a new artboard cause it implies at least renaming and reorganizing...
At least the artboard should be able to stick to the object when the resize it. The same way that objects can actually stick to the artboard when you resize them.

@Arnaud Mez But Styles are application wide.
Create a new Style Category (perhaps called "Strokes") Draw a line and set your  preferred line weight, join type, cap type, pressure profile, colour. Create a new style from selection, and rename it to something appropriate ("4pt Black Wobbly") Repeat until you have a library of strokes that you commonly use. These are now available in every document you create, and can be exported / imported to share between devices.
To me this is exactly like creating a palette of colours, and I can't really imagine a simpler way for it to work.

Hi @StuartRc see how many steps you take to achieve a simple thing that should take a simple click and draw ?
That why it's a great to make it possible to save line/stroke profile application wide for reuse on any project (new or old) without having to redo/reinvent the whole thing.
Not only that, it will help us not feel reject because we have not a blazing or killing drawing tablet with pen pressure functionality when we love our already existing but great mouse.
Thank you so much for your input !
Much appreciated.

Hello !
@Patrick Connor, @AdamW, @MEB and other team member, i just hope you are really taking it and resting and enjoying staying with your friends, family etc... and not touching your laptops for this week-end.
i'm dropping something here for Affinity Publisher (and also the whole product line) but not expecting you to answer or contribute during the week-end, you deserve good rest.
Well, this is a proposition i've been continually forgetting to log here.
Using Publisher (but also Designer and Photo) in our workflow (for those who integrated it already before stable version) we often and even make massive use of stroke and tweaking it is part of our every day thing; i see there is possibility to set a stroke profile after playing with the curve thing to make its aspect fit our need; after doing that curve thing we can save the profile ... but i noticed this, the saved stroke curving profile disappears after saving closing the project (case 1) and we have to remember how it looked like and redo it 
my request is this, would it be possible to save stroke curve profile as application wide usable thing, like we continually do with colors/gradient palette so we can simply reuse it with old projects or when starting a fresh project ?
i often watch the brothers from Design Art Studio, Olivio Sarikas and even @Bri-Toon tutorial on youtube and for each new projects they have to redo the line stroke profile tweaking over and over for that project, which you must admit is really time consuming.
i would rather, setup a stroke curve profile, save it and know it's application wide (like color some palette) and not document based only and then simply select it in the stroke tab before i draw a new line, then draw my line using pen/pencil tool with that selected profile and see if it fits my desire, this will be helpful for those still using mouse technology and even for those using pen/graphic tablets lacking pressure sensitivity functionality to feel home but also to feel and work with less stress or see their head overheated trying to think or remember how this used to work or to be but just focus on their design and produce great things.
Please make the curved stroke profile saving applicable application wide in Publisher and if it has the success it should have, then replicate/expand it to Designer and Photo.
@firstdefence, @Petar Petrenko, and all others ... your inputs to round the corners of this idea/proposition is expected and will be of great help !
Blessings !