How to apply Levels or Curves to an Alpha?

[rui_mac]

Yeah, I know I'm carrying "Photoshop habits" over to Affinity Photo and I must learn how to deal with a completely new application with its own paradigms.

And, or course I don't always use the Solid Color/Flat Object + alpha method.

I only used those methods extensively on the video I created to show that alphas are just plain 8 bit (or 16 bit) images and we should be able to do with them EVERYTHING that we could do with a greyscale document.

One of the methods that I use often to start creating masks is to use one of the RGB channels (or a combination of two) as a starting point.

Just like you can see in the video I made to show that, for Affinity Photo:

Even if the Refine mode is quite nice, sometimes we really need to get down and dirty with the channels. And being able to perform operations with those channels and alphas is a must.

[aitte]

That's a very good use of individual channel access. There is no "Combine Channels" action in Affinity Photo because it doesn't need it. You can do it by combining individual channel selections instead.

 

Try this:

1. Load the photo of the elephants, you used this one: http://www.howitworksdaily.com/wp-content/uploads/2015/05/tanzania_elephants3.jpg

2. Look in the "Channels" panel, and click the various red/green/blue channels to find the ones with the best contrast. I think you decided on red and green in the video.

3. Right click the "Composite Red" layer and choose "Load to Pixel Selection".

4. Right click the "Composite Green" layer and choose "Add to Pixel Selection". This adds the intensity-values of the green channel to the intensity of the previously selected red channel.

5. Click the "Return/back" arrow in the top right of the Channels layer to return to viewing all colors.

6. From this step onwards, there may be better ways to do this than what I am about to suggest... I haven't delved that deeply into Affinity Photos' channels and masks yet, and it seems it has the ability to "create spare channel" if you right click, and even toggle quick mask (if you look at the "Pixel Selection" in the channels list), etc, so there's probably a more advanced way than what I am about to suggest next...

7. Create a new pixel layer.

8. Go to Edit > Fill and fill the selection with white.

9. Deselect the current selection.

10. Create another layer below your new one, and fill it *completely* with black. This is just to provide contrast so that you can see your selection/alpha work...

11. Now edit the white layer; do your levels, threshold, dodge, etc there. I suggest making a selection around the little elephant, then inverting the selection and hitting delete to get rid of the pixel data for all other elephants. Then refine the little elephant until its outline is just pure white (just like in your video).

12. When you are done making a white mask for just the tiny elephant, go to Select > Selection From Layer and you're now ready to save that final selection as a mask.

 

If there's an even better way to do this in Affinity Photo then I'd love to know it.

 

And of course, they're planning to improve editing (maybe even using adjustment layers) on masks too, so this will get even easier later.

[rui_mac]

The problem with that approach is that we are limited to only do what the Calculations in Photoshop allow with Linear Dodge (Add) and Multiply.
But most of the time I need to combine channels with Overlay, or Darken or Lighten, and sometimes other modes. But Overlay is used VERY often.

Also, combining channels with optional Invert and percentage is very helpful. In Affinity Photo I can invert the selection, I know. But if I want to combine, lets say, the Green channel with 50% of the inverted Blue channel, in Overlay... it is not possible.

The methods to extract and combine channels information, in Affinity Photo, are still very limited.

[aitte]

That's still doable like this:

 

Select the green channel, load to selection. Make a new layer, fill with white and call it "green alpha".

Select the blue channel, load to selection. Make a new layer, fill with white and call it "blue alpha".

Invert the "blue alpha" layer, set its blend mode to overlay and set it to 50%.

 

It's a few more steps than "Calculations" in photoshop, though... But maybe we have more control in the end? Since you can use individual effects on the two separate layers, and then "Merge" those two layers into a single one.

 

I agree though, it would be nice if there was a "calculations" command built in. It saves a lot of clicking.

 

 

 

 

PS: Are you aware that you can right click on a mask and choose "Edit Mask" to get a black and white view of the alpha, with full ability to make selections, apply gaussian blurs, perspective, etc? Of course there's no levels or curves, since those only exist as adjustment layers... but all destructive effects work.

[rui_mac]

Yes, I'm aware of that. And I do expect that it all develops further so that there are no restrictions or different paradigms.

And has it is now, it is still a whole lot of work to do things that should be simple :)

[aitte]

Yep, there are some things that Affinity Photo lacks right now. The greatest weakness I've found so far is the Text Tool, which is very basic. It can't adjust the space between lines (many fonts have too tall line-heights which causes a lot of whitespace), it can't do fake-bold/italics (for fonts that don't support it), can't do curved/arced text effects, etc. But I think I heard they're going to improve font effects.

 

For most things, Affinity Photo has everything Photoshop did or even better.

 

In some areas, it's a bit weaker but it'll improve with time.  :lol:

[rui_mac]

There are things in Affinity Photo that I think that are better than Photoshop :)

As for the Leading, you can adjust it. Even manually. Just select the line and press Alt+Up Cursor key or Alt+Down Cursor key.

And I also miss faux bold/italic. I can mimic it using Stroke effect and Slanting the text box... but it is a workaround.

But it will get better, I know. It is already excellent :D

[aitte]

Ohhh so line-height is called Leading. I never knew, since the corresponding Photoshop setting only has an icon (no name), so I just assumed this name: http://www.w3schools.com/cssref/pr_dim_line-height.asp. 

 

Thanks for that! The setting is found under the Paragraph button: Leading. That's one thing to check off the wishlist.

 

 

And italics can be faked with Character button: Shear, with perfect results.

 

 

The faux-bold workaround is incredible too! The text toolbar has a Stroke option. Set the "Join" option to the totally sharp corners (last option) and the result becomes crisp and better than photoshop, since it gives total control over the stroke width (boldness). And if your characters start intersecting with each other, just open the Character button and increase the Tracking (space between letters). The only problem I discovered with the "stroke" feature is that it doesn't look good together with fake-italics ("shear"); it almost looks like a 3d dropshadow instead, but luckily I almost never need to use faux italics and faux bold together.

 

 

Excellent information. Funny how we both give each other tips for working with this new app, that the other had missed. Now I can finally rely on its text tool without feeling limited. Turns out all I am truly missing is the text arcs (and curving text along a path), but I don't use those very often, and I read that the devs want to add it someday.

 

 

Affinity Photo continues to impress! Let's hope the devs will read this thread and consider adding Calculations and the ability to do adjustment layers (like levels) on masks someday as well. ;-)

[rui_mac]

Leading (reads "Leh-ding", not "Lee-ding") comes from the old-school printing process of "moving type". They used strips of lead to create space between lines.

I'm from Portugal and even professionals misspell the word "Leading", pronouncing it "lee-ding". That if because they don't know its origin. :)

[Artturi]

So can I now apply the levels to the layer mask somehow? I'm trying to figure out how to remove parts of the image and leveling the layer mask is the only way to do that. 

[anon1]

Sure

Apply the layer adjustment and choose "alpha" instead of "master" channel

 

Cheers

[velarde]

Hello MBd. 

 

Care to elaborate al little bit on this please.?

Maybe a screenshot.... Looking to do this for a long time.

 

 

Can't find where todo what you mention here.

 

thanks

 

 

 

Sure
Apply the layer adjustment and choose "alpha" instead of "master" channel

Cheers

[anon1]

sure

 

[velarde]

Thank you MBd

 

This is very helpful to learn to do it the Affinity way.

 

This thread is 2 years old... ja . Has this option been there are along?

 

Never would have found it... 

[anon1]

I don't know if it has been there since the beginning but I think it has

 

some features were not easy to discover at first

 

I was one of the first writing about blend if e.g. which nobody had a clue how to use in the beginning 

but now most features are relatively well known I'd say 

I took a stab and documented some important ones here https://forum.affinity.serif.com/index.php?/topic/37125-ap-ad-beginner-amateur-pro/

 

cheers, glad it helped took me some time to discover as well 

[Artturi]

Wow, amazing, this small trick made my life so much better. Thank you!

[quinnballard]

@rui_mac Have you had any luck with this? I've been trying to hunt down the same feature for AP, too, but don't know if it's available or where it is.

 

I'm looking for a Levels Adjustment for the image to use for the exact use case for masks that you had originally mentioned. On Photoshop it's Image > Adjustments > Levels, but I can't find it on AP. The only thing I can see in AP is an Layer Image Adjustment, which isn't the same thing. I'm attaching a screenshot from Photoshop of what I'm looking for.

[MEB]

Hi quinnballard,

Welcome to Affinity Forums

Check the clip below (it may take a little to load):

 

 

[quinnballard]

@MEB Thanks so much – that was exactly what I was looking for. I was overlooking switching to the "alpha" channel. That vid was so helpful – wasn't sure where to find the Alpha channel when previously looking through this forum. Thanks again

[sprayer]

On 12/8/2017 at 2:42 PM, MEB said:

Hi quinnballard,

Welcome to Affinity Forums

Check the clip below (it may take a little to load):

 

 

 

I am finding what this is not works if i open psd with mask layer(what already was applyed levels in photoshop). it works only if i making a new mask.  

[MEB]

Hi sprayer,
Welcome to Affinity Forums
Do you mind attaching/uploading the PSD for us to take a look?

[sprayer]

Hi  MEB,
Sure,  please see attached file

Vature_15_RestoringRadianceEyeSerum.psd

[MEB]

Thanks for the file. I'm not sure I understood your issue though. This PSD file doesn't have any levels adjustment, only a mask applied to the main [R,G,B] layer. You can nest a Levels or Curves Adjustment to this mask to tweak it's alpha (don't forget to change the channel to alpha) and it works as expected. Can you expand a little on what are you trying to achieve? Maybe I'm missing something here.

[sprayer]

Thanks MEB, sorry about that.
I am new to affinity still trying to migrate from Photoshop, didn't know about grouping layers, if you making mask layer and moving it to apply to another layer is has one "group" don't know how it named, but in PSD mask placed at deeper "group", so then i was move levels adjustment layer to first layer and psd mask was at another "group" and it did't see mask layer

But still i think something wrong, it's work but not always. please see attached videos they are from the same file, i just moving a bit orders but in the end they are in the same i believe position, but in one video is works in another not working. 

[MEB]

You have to drag the Levels adjustment over the thumbnail of the mask (you should see a small vertical blue line immediately on the right of the thumbnail while you are dragging the adjustment over it). This will nest (this operation is referred as Layer Masking in the help and video tutorials) the adjustment to that mask - if you do this correctly you should see both the image thumbnail, the mask thumbnail and the adjustments thumbnail lined up when you collapse the image layer in the Layers panel. If the levels adjustment thumbnail doesn't appear when you collapse the image layer it's because the adjustment was instead clipped to the image Layer and not nested to the mask. See images below:

This is what you want - the levels nested to the mask (this operation is referred as Layer Masking in the help and video tutorials):

The same layer structure as above when the image layer is collapsed (notice the three thumbnails for the image, mask and adjustment):

 

When it doesn't work it's because the adjustment was placed inside the image layer (this operation is referred as Layer Clipping in the help and video tutorials) - notice the different indent between the mask and levels adjustments thumbnails):

The same layer structure as above when the image layer is collapsed (notice the levels thumbnail missing):

 

Check this video tutorial for more details: Affinity Photo - Clipping vs Masking