Transparency/masks/alpha in Photoline

[dennisqdw]

Hi all. Ok I've been a long time Photoshop user, and have moved to PL for many of the same reasons most of you have. There's one thing that just baffles me, and I've had to give up on figuring it out myself. It appears that there aren't alpha channels the way I'm used to in Photoshop, and it appears that if one has a transparent layer you can't just make a lasso box and then fill it with a color they way I'm used to, and on and on. The PL documentation doesn't seem to explain this well (or I haven't found it). Has anyone written up either a good explanation of this topic for PL, or even better some help for Photoshop users to make this transition in approach/thinking? Can anyone here point me to some sort of forum thread or webpage? thanx in advance.

--ds

[Herbert123]

Hi Dennis,

Welcome to PhotoLine! I had been a long time Photoshop user since version 3.5, and switched to PhotoLine about three years ago. I still have to use Photoshop at times in my teaching job, but otherwise it is PhotoLine all the way for freelance and personal work.

1) selections (lassos) and fills: create a selection (lasso) and use the fill tool to fill the selection with the colour of your choice. This works the same as in Photoshop. Unless I misunderstand your question?

2) Channels

Channels work quite differently compared to Photoshop. In some regards the same (for example; when you select an adjustment layer, the layer mask shows up in the channel panel, and it is possible to enable the visibility of that channel in the view, just like Photoshop). But the main difference is that it is not possible to work directly in a channel by selecting that channel in the channel panel. Instead, the relevant bitmap tools have integrated buttons to select channels, and you can turn these buttons on and off to work in a specific channel.

This works quite fast, and is actually simpler and more straightforward for a lot of direct channel editing, but what if we need to apply a filter to a specific channel? Same workflow: all (or most) relevant filters again allow for a quick channel selection. And one of the advantages of this workflow is that it is completely non-destructive, if required.

For example, let's assume we wish to apply Unsharp Mask to the L channel of Lab mode of an image layer only.

In Photoshop: a) select the layer and convert layer to a smart object. b) open the smart object, and switch to Lab mode. c) switch to the channel panel, and select the L channel. d) apply Unsharp Mask (destructively!!!). e) save and close the smart object.

In Photoline: a) select the layer b) add the Unsharp Mask adjustment layer. c) Switch to Lab in the image mode dropdown, and select the L channel.

Compared to Photoshop, PhotoLine's way of working with channels is (generall) A) more efficient, B) simpler, and C) non-destructive!

Yes, work-arounds exist to mitigate some of this destructive (layer) mask/channel behaviour in Photoshop, but far more steps are required.

Any caveats? Yes, as always you win (a lot in this case, in my opinion), but we lost a bit as well.
1) we cannot save selections to a channel. Instead we will have to save those in the layer stack, for example in a hidden group. I find this a bit awkward at times. This is the thing I do miss. Saving selections in the layer stack feels... wrong to me.

2) usually, in most circumstances we do not need to edit the channels directly - all the relevant tools, filters, and effects allow us to work on and with specific channels. Yet sometimes we might need to edit a channel directly, or directly perform operations on it. In this case we have to copy the channel of our choice to a layer (with the Channel to Layer button in the channel panel), do our thing, copy and hide the layer, and use the Change Channels command to copy the edited channel back into the channel of our choice.

In a nutshell: in 98% of all cases I found I never have to work with channels the way I did in Photoshop anymore. In PhotoLine all relevant tools have the channels built-in, and it is very simple to work with them. And PhotoLine allows us to work non-destructively with many filters and adjustments on specific channels - even on one layer only, or a group of layers. This is not possible in Photoshop. But the drawback might be that PhotoLine requires more steps to perform a direct channel edit compared to Photoshop. Compared to how I had to work in Photoshop with channels, I prefer PhotoLine's workflow. It is far less destructive, and simpler in the large majority of cases.

One crucial thing is UTTERLY different compared to any other image editor I have worked with compared in PhotoLine (outside node-based compositors): the concept of an "image mode" is completely different. In PhotoLine the user can work with a file in image mode or in document mode. In image mode the background layer, or bottom layer defines the "final" colour space. To "convert" a RGB document to a CMYK or grayscale one, merely change the background image layer's image mode in the layer properties' Type.

To be more exact: any bitmap layer in PhotoLine can be in any colour space and bit depth. Let that sink in for a minute - it means we no longer need to convert layer content to a specific image mode. It also means that when we change the background layer to grayscale, and back to RGB NO INFORMATION IS LOST in the layers in our composition. I keep an empty bitmap background layer which I can convert to any colour space (image mode), and none of the information in the other layers is lost! Very cool. (In Photoshop this is also possible through the use of smart objects, but the major disadvantage is that content in smart objects cannot be edited in real-time and in-place).

When working in Document mode, the colour space is defined by the colour profile (ICC-profile) you assign to the document. Oh, and it is possible to assign custom colour profiles to individual layers as well for colour conversions. Pretty amazingly flexible.

Hope this helps a bit in your understanding of PhotoLine. Some concepts and workflows are quite different compared to Photoshop.

PS Version 20 is around the corner, and introduces a number of rather splendid new features.

[photoken]

Yet sometimes we might need to edit a channel directly, or directly perform operations on it. In this case we have to copy the channel of our choice to a layer (with the Channel to Layer button in the channel panel), do our thing, copy and hide the layer, and use the Change Channels command to copy the edited channel back into the channel of our choice.

Nice explanation of the differences between PS and PL.

Can you give an example of that channel editing/operations you're talking about?

[Herbert123]

Yet sometimes we might need to edit a channel directly, or directly perform operations on it. In this case we have to copy the channel of our choice to a layer (with the Channel to Layer button in the channel panel), do our thing, copy and hide the layer, and use the Change Channels command to copy the edited channel back into the channel of our choice.

Nice explanation of the differences between PS and PL.

Can you give an example of that channel editing/operations you're talking about?

I used to work with direct channel operations in Photoshop on a regular basis, but in PhotoLine it is something I seldom have to do. For example, sharpening or blurring a specific channel in Photoshop can only be done with a direct edit in the channels palette. Such basic moves are non-destructive in PhotoLine, and easy (easier?) to perform as well.

But sometimes I needed to replace one RGB or CMYK channel with the information from another - for example the L channel in Lab, or mix another cleaner channel with less noise/artefacts. In Photoshop it is a quick copy & paste - it is very direct. In PhotoLine I use the "Change Channels" command, which, while it is non-destructive (great!), does feel rather indirect, and there's a bit of a disconnect in that I cannot view the channel(s) content directly.

At times I just want to work with the channels directly, and that is just much more direct in Photoshop.

It is the same with direct pixel manipulations: while direct destructive channel operations hardly come up anymore at this point, the one thing that DOES get in the way on a regular basis (for myself and a number of other users) is that PhotoLine will not allow for a lasso that manipulates pixels directly. I really wish the Lasso tools would include a "direct pixel manipulation" mode. It makes PhotoLine almost impossible to work with for pixel art and retro game art - and more difficult than it ought to be for GUI stuff at times.

[dennisqdw]

Herbert123, thanx for the very thorough explanation. It encourages me to stick to my decision to use PL. It also told me that I needed to explore the problem I'm having with filling selections a little more carefully.

1. Say that you have a "transparent" layer (that is you see the pattern of little white and pink boxes), and you have the "show mask" icon active, then when you draw a square lasso for example, you will instantly see the green mask and it will be clear to the pink and white pattern where the square selection is drawn, and will fill with a color as expected. So far so good.

2. But let's say that somehow, and I'm not exactly sure how or why this happens,( in my case it happened by copying and pasting a smaller image into a larger image), when you draw the square lasso, the mask is only seen where the smaller image was pasted, and everywhere else is "clear" to the pattern. In that case you can't fill the selection square in the clear part, only on the green mask part.

3. So I'm guessing that this has something to do with changes being allowed where the mask is (which to me is a little counterintuitive, as I would think that the mask "protects" an area from being changed as opposed to allowing an area to be changed, but ok, I'll work with it the way it is), so in photoshop I would just go to the alpha channel and change the mask layer to fill the whole image. But here of course I can't do that. I tried to click on the Edit Mask button, thinking that I could fill it with black or white and change my mask that way, but that doesn't work. So here's where I give up

4. So if it's not too much trouble could you please explain to me just how masks work in PL; the relationship between masks and alpha (and in PL alpha doesn't seem to refer to an "alpha layer" like it does elsewhere, so I'm not even sure what it refers to); and how one can "fill" an image with a mask, i.e. make it all green so that selections will then work as expected; and finally trivially, why can't I see the green mask when I have the show mask button on, unless I've made a selection box.

thanx again in advance. --ds

[bkh]

2. But let's say that somehow, and I'm not exactly sure how or why this happens,( in my case it happened by copying and pasting a smaller image into a larger image), when you draw the square lasso, the mask is only seen where the smaller image was pasted, and everywhere else is "clear" to the pattern. In that case you can't fill the selection square in the clear part, only on the green mask part.

Sounds like the "problem" is that the pasted layer is smaller than the background layer. Layers can be any size in PL (if I remember correctly, all layers in PS have the same size). Now if you select a layer and try to paint/fill it outside its borders, nothing will happen. Depending on your workflow, you could merge the pasted layer down into the background layer, extend the pasted layer (using Layout -> Image -> Bring to Document Size), or create a new document sized transparent layer for painting/filling.

Cheers

Burkhard.

[Herbert123]

Yes, Burkhard is correct: as opposed to Photoshop a bitmap layer in PhotoLine can be any size (including much larger than the original's canvas). I assigned a shortcut key to the "Bring to Document Size" to have quick access when I need a layer to be the size of the document/image.

[photoken]

ds,
The terminology that PL uses is very precise, but it is a bit different from the terms used in other image editors.

To begin,
In other image editors, "selection" refers to both the marquee and the content of the marquee. This is confusing, but we're all used to it. PL makes a precise distinction between "Mask", "Lasso (the marquee)", and "Selection":
The "Mask" is a grayscale image, ranging from black to white and having intermediate gray values, that defines the image area being targeted.
The "Lasso" (the marquee) is a vector representation of the Mask, the marquee line being the points of 50% gray between the black and the white areas of the Mask.
The "Selection" is the image content within the Lasso & Mask, varying in opacity according to the black, white, and gray values of the Mask.
In other words, when working in PL, one has to essentially forget about the word "selection" until you want to actually modify some image pixels.

This mini-tutorial demonstrates the relationship between the Lasso and its Mask:
http://www.pl32.com/forum3/viewtopic.ph ... 434#p32252

Unfortunately, PL uses the word "mask" to refer to both the area being targeted (the marquee, as explained above) and the layer mask which determines the transparency of areas within the layer. So, you always have to remember the distinction between a Layer Mask and a lasso's mask. They are two separate things and can co-exist. This should help explain your question #3....

Your question #4 seems to refer to using Layer Masks. You "fill an image with a mask" by using the Layer Mask icon at the bottom right of the Layers panel to create a layer mask for the layer. Or, you can use the main menu item Layer...Layer Mask...Create (Ctrl+Shift+X).

[Herbert123]

#4: turn on the "special channel" instead in the channels panel to view the mask overlay. No need for a selection in that case.

A lasso (selection outline) can be separate from the mask. You can turn on the mask overlay in the channels panel, AND also create a new lasso (selection outline) that selects part of the current mask. This works just like in Photoshop. In Photoshop you will not see a mask overlay unless the layer mask channel is displayed in the channels palette.

I know this can be confusing at times, but it is actually quite handy: if you need to remove part of a mask quickly, you simply turn on the special channel mask overlay, and use the regular selection (lasso) tools to cut away or add to that mask by using the delete key and setting the background colour to white or black (same as Photoshop: X to alternate between the background and foreground colours, and D to reset to black and white).

ALT-clicking on a mask reveals its greyscale mask. CTRL-click to load a mask, and show the overlays via the mask button in the tools panel. Then click the top right mask icon with brush to start adjusting the NEW mask - not the existing one in a (for example) layer mask. To edit the existing one with a mask overlay, turn on the special channel in the channels panel. This is different from Photoshop.

One more trick on the side: use <ctrl>-mousewheel to zoom in and out of the layer and channel panels. WAY more freedom than Photoshop's limited thumbnail size choices. Also works with the browser, document, and pages panels. Sometimes I want a better view of my content in the channels and masks.

And double-click on any of the mask icons at the bottom of the tools panel to open the mask color overlay settings.

PS: when you save a file with an active lasso, that lasso will be saved as well. Next time you load up the file, the lasso is still there.

[dennisqdw]

Thanx to all of you for the many helpful answers. I hope that this will also be of value to other new users of PL. Give me a day or so to explore all this new detail. If I don't write again that means I get it now, and I'm good to go. yours --ds