I covered the subject in a video. I spoke too fast, I think. It’s worth looking at though.
The clue about Apply Image is in the name. You can only apply something to the image you have open on the screen. That can be a layer or a layer mask or a channel.
It’s fair to say that Adobe does not really give you much information about Apply Image.
Apply Image has been around for many years, it’s a legacy tool that Adobe hardly ever mentions.
Some Photoshop experts will show you some wild and wonderful image edits using Apply Image. To be honest, some edits with Apply Image are more interesting than useful – and can be easily done without resorting to Apply Image.
Anyway, let’s get started.
What does Apply Image Actually Do?
Apply Image applies a Blend Mode to the Target which can be the Layer, Layer Mask, or Channel you are seeing on screen), using a Source.
You must have the layer, layer mask, or channel selected and visible for it to be the target.
The Source is normally the image you have open. But it can another image, of the same pixel dimensions and bit depth.
What are the Options for Source?
From the Source you can choose:
- An individual layer
- All the layers (Merged)
- An individual channel Red, Green, or Blue
- RGB Composite Channel.
- An Alpha Channel.
- You can also choose to Invert the channel/s. As channels are greyscale; with invert you are turning white to black, and black to white and inverting all pixel luminosity values in between.
What are the Options for the Target?
Within the target you can be on:
- A blank layer.
- A layer with pixel data.
- An individual channel.
- RGB composite channel.
- A blank Alpha Channel.
- An Alpha Channel. (Mask).
- Layer Mask.
- You change the opacity of the output.
- You can also Preserve Transparency.
- You can output the result via a Mask using a merged or individual layer using a channel.
- Finally you can also invert the result.
Are you still here?
The Many Permutations with Apply Image
By now you should realise there are just too many permutations to predict what results you are going to get in advance.
Unless you stick to tried and tested methods like Frequency Separation you are just stabbing in the dark.
I don’t think there’s anyone on this planet who could tell me what result you are going get for all the permutations you can have.
So, don’t worry if you don’t understand it. Just try and stick to one or two methods using Apply Image.
Apply Image is useful for
- Frequency Separation (used for skin retouching).
- Creating simple luminosity masks.
- Refining or creating Alpha Channels for use as masks.
Apply Image Workflow
- Target Image is always the image you have open.
- Using the Target image, select either a Pixel Layer, Layer Mask, individual Channel, RGB composite Channel, or a blank layer you want to apply (the clue is in the name) the effect to. This now becomes the Target.
- Go to: Image/Apply Image… Make sure Preview is ticked. With Preview ticked you can see the results in the Document Window in real-time.
- Set the Source Document, which defaults to the image you are working on. So, in normal use, the Target image and Source image are the same. You can pick another Source image, only if the image is open, and of the same Pixel Dimensions and bit depth.
- Then choose the Layer, Channel, or Transparency you intend to Apply Image to. Then choose Invert if necessary. Please note Merged (merged layers) will be an option if you have more than one Layer.
- Pick the Blending you want. There are two Blend Modes called Subtract, and Add which have additional controls of Scale, and Offset. All other Blend Modes behave in the same way as normal Layer Blend Modes.
- Change the Opacity if you wish or, Preserve Transparency, or output the result via a Mask.
The Source is normally the image you have open. But it can another image, of the same pixel dimensions and same bit depth.
- Target = Channel, Layer or Layer Mask you have selected in advance which is also visible (with the eye icon).
- Blending= Any Blend Mode. Add, and Subtract give you access to Scale and, Offset.
- Opacity = You can make the effect of the blending less opaque if you wish.
- Scale = Only available with Add and Subtract. The scale divides the result of the Add and Subtract. A scale of One (1) has no effect, two (2) has the maximum effect. Any number above one, to three decimal places, will make the result darker, i.e. 1.578.
- Offset = Only available with Add and Subtract. The result of the Scale is passed to Offset. Offset has a range of 255 to +255, to darken, or brighten.
- Preserve Transparency = Only the opaque pixels will be affected.
- Mask = Output the result of the blending via a mask.
Apply Image with the mask showing
The two Blend Modes Subtract and Add are the most flexible because they give you access to Scale, and Offset.
In the scenario above we are subtracting the luminosity of the Source, Composite Channel (RGB), from the Target. Using the same image.
Simply put we are subtracting the overall luminosity of the “Target” using the Source Layer’s overall luminosity, or grey value.
It helps to think of Target’s pixel grid laying on top of the Source’s pixel Grid in the same way the subtraction works in maths.
I am not entirely sure what numbering system is used in Apply Image, as Adobe does not divulge this type of information. For all, we know it could be a mixture of integer methods.
But, using the 0-255 system works well to explain with this scenario, where Zero = black, and 255 = White, even if it’s not the Integer system Adobe uses.
Apply Image Example
Subtract Blend Mode
I want to push this home – try and visualise the target’s pixel grid on top of the source’s pixel grid.
The Target is always on the top
The source is always on the bottom.
Let’s say we have two hundred luminosity Pixel Value on the Target layer’s pixel grid.
And the Source pixel has the value of one hundred in the same place as the Target on the pixel grid.
So, the Target is brighter than the source as 200 is brighter than 100 on the 0 – 255 scale.
With subtract — 200 minus 100 = 100 (Target minus Source)
The result is now darker.
Subtract will always Darken and Add will always lighten.
Scale Divides & Usually Darkens
The scale runs between 1 to 2, and any value between up to three decimal places.
The Scale divides the result from the Subtraction or Addition.
A scale of One has no effect for instance 100/1 = 100 (One hundred divided by one change nothing)
A scale of two has the maximum effect
For a Scale of two:
100 divided 2 = 50 – making the image darker.
Note: As dividing any number by one, changes nothing. Any scale number above one will result in a darker result with softer transitions.
Offset to Darken or Brighten
The final stage is the Offset, ranging from -255 to +255.
The reason for such a wide range is that it’s entirely possible to have a number below zero. Yes, darker than black but only mathematically.
For instance, we can have, minus two hundred luminance. Black is zero in the 0-255 scale So, minus two hundred (-200) only exists as a number. So, we humans will see black, but the number is in fact minus two hundred (-200).
We use Offset to bring the result back to the visible range of human eye of 0-255.
In this scenario, a positive Offset of 128 would make it brighter.
50 + 128 = 178
Opacity can be useful sometimes if you want to lessen the effect of the blending.
Mask… looks complex, it isn’t. Mask simply outputs the result of the blending via the luminosity of a channel, or area of a selection. By the way, a selection is seen as an Alpha Channel by Photoshop, but you will just see the marching ants.
Let’s say you use one of the colour channels. Anything that is white on that channel reveals. Anything that is black will conceal. And grey will allow results to show depending on how near to white it is.
A little-known method is to select an area on an image first. Then run Apply Image, and everything will be output via the selection. The confusion might come if you want a selection as a Mask, which as in the example above. which is counterproductive.
You might find it useful to learn verbatim Frequency Separation for portrait retouching.
Here’s a link to an article I’ve done Frequency Separation.
Play around with Apply Image as part of your Photoshop learning curve. To be honest, don’t waste too much time on Apply Image.