Can Photoshop knock out white (or any other color) yet?

[jyeager11]

Is there a simple way to knock out white (or any other color) in Photoshop CS5?

It's hard for me to imagine that in this day and age, doesn't have an easy method of doing what this plug-in allowed us to do over a decade ago.

Surely, by now, I can stop installing this plug-in (originally created for PS on Win95).

[Noel Carboni · Accepted solution]

I don't follow links as a rule.

What do you mean by "knock out"?  Are you trying to make an image partially transparent?

You can select parts of an image in Photoshop via a large variety of different methods in Photoshop, from color ranges to manual lassoing, then either delete through a layer or add a layer mask to make those regions transparent.

I've used Photoshop for 16+ years now and haven't found a need for a 3rd party plug-in to help me make selections yet.

-Noel

[jyeager11]

I don't explain things when a link has been provided as a rule.

I'm not talking about selecting. I'm talking about automatically knocking out a color (in the case of the link provided, white) with all alphas included.

[Noel Carboni]

Okay, just for you I made an exception and followed the link.

The explanation there was all but useless.  It seems I correctly interpreted your "knock out" terminology to mean that you wish to create transparency.

I suspect there's a fairly direct method to recreate its effects involving selecting first, then other manipulations, but I don't plan to research this old plug-in any more to try to help you.  If you're unwilling to post any better description of just what you're trying to do, then good luck to you getting help.

-Noel

[Guest]

In addition to what Noel said white is not a color, or different rules apply if you want to "knock it out".

[jyeager11]

Curt Y wrote:

white is not a color, or different rules apply if you want to "knock it out".

With a simple CTRL-U, we can select reds and make them more saturated. Or darker. Or change the red hues to any other color. And we've been able to do this since as far back as I can remember using Photoshop.

Why can't we turn that red transparent? Knock it out?

Think of how useful it would be in a bluescreen or greenscreen scenarion. You've got shots of a model on a green screen. You want to knock that green screen out, but not by selecting it... because you want the green that bled into the main subject to also alpha itself out. Just consider how much of that green made its way into the model's hair, in the thinner areas.

What do you do?

The long way will take hours to do right (using the wand, refined selecting, masks and brushes). But if you can somehow knock out the green automatically, like they do in video editing software, you're saving those hours. Imagine if video editors had to do it with wands, refined selecting, masks and brushes when they have 28 frames per second to fix.

Cybia Alphaworks will do it, but only with black or white.

[jyeager11]

How much more clear do you want to be than "knock out a color", Noel? By all means, I welcome you to list me the myriad of ways this expression can be taken, other than turning a color transparent.

Additionally, how much of a better example can I provide than a link to a plugin that does exactly what I'm talking about, in case there was any confusion left over?

But you didn't even want to bother clicking on the link the first time. That tells me that you're not really willing to help. And your further replies just prove it.

So please, if you're done pretending to want to help, move aside and allow someone who genuinely won't mind making an effort do so.

[Guest]

I am not very knowledgable about plug-ins, but it is my understanding that all they do is use existing photoshop tools through a series of actions to achieve the results.  One can do the same thing on his own wilh a little effort.

[jyeager11]

Curt Y wrote:

I am not very knowledgable about plug-ins, but it is my understanding that all they do is use existing photoshop tools through a series of actions to achieve the results.  One can do the same thing on his own wilh a little effort.

Clearly, we do not have the same definition of "a little effort".

Knocking out a bluescreen behind a model with the wand, refined selecting, masks and brushes can take hours to do right at high resolution.

Video designers work at 28 frames per second. They're not going to spend 2 hours per frame on a 10 minute scene. They have software to knock the blue out and replace it with another background video. This is how most car scenes are done.

I'm amazed to learn that no one thinks such an option would be useful in Photoshop. For the love of Christ, if I've got 20 pictures of a model standing in front of a blue screen, and I need to place her on top of various backgrounds... can NO ONE see the advantage of an option that would automatically knock out the blue, including the edges where the model outline meets the blue background, turning the blue invisible while retaining all the other colors so that she can be seemlessly added to ANY background with minimal editing... and all the antialiasing remains?

[Guest]

mjyeager wrote:

...I've got 20 pictures of a model standing in front of a blue screen, and I need to place her on top of various backgrounds... can NO ONE see the advantage of an option that would automatically knock out the blue, including the edges where the model outline meets the blue background, turning the blue invisible while retaining all the other colors so that she can be seemlessly added to ANY background with minimal editing... and all the antialiasing remains?

Beware that these color to alpha/transparency plugins typically affect the entire image. They do not care if the color to knock out is within the subject.

For a situation like you describe, you may want more than what these plugins do. There are some nifty masking/selection ideas here.

[Noel Carboni]

Select the background (by color range, with the quick selection tool, with the magic wand tool, and/or a dozen other ways), refine the selection as needed, then delete.  Voila, transparency.

People have been doing this for ages - clipping people out of backgrounds that are less than perfect.  It can be done quite quickly, but it's rarely a trivial process.  I have no doubt that a plug-in might have provided a way that you liked to do it, and I also have no doubt that it could be done other ways.

You have not been specific about what color (white?  blue?  green?), how much detail is likely to be at the edges, nor how well you want it to work.  Do you want to cut models out of 5000 x 3000 pixel pictures, preserving every strand of hair, so that the job is invisible in prints at thousands of ppi?  It's doable.  Or are you doing web images?

Post a representative picture; I'm sure there are people around here who can show you how to do it in short order.  If you're dealing with a pretty consistent background color someone could probably even put it in an action for you.

-Noel

[jyeager11]

Noel Carboni wrote:

Select the background (by color range, with the quick selection tool, with the magic wand tool, and/or a dozen other ways), refine the selection as needed, then delete.  Voila, transparency.

Doing this right takes hours per photo.

Sure, it's easy if you're cutting out a cartoon character with a clear outline, or if you're doing junior or intermediate-level work... but some of us want the cropping to look seemless. What do you do about a moving object, and the motion blur therein? How much time are you going to spend with that wand, those masks and that brush to get that right?

What about an immobile human being, with strands of hair interacting with the flat-colored background with various degrees of blur? And what do you do about the sheer silk dress the woman's wearing that allows various degrees of the background color to show through?

You only read half of what people write before responding to them, and it shows in every reply you add.

However, if you could knock out the unique-colored background as easily as you could change its hue, you would save hours on this one picture alone. How many would you save after 100 pictures?

PS: I'm still waiting for you to explain how the words "knocking out a color" could mean anything but what it obviously means, since this confusion caused you to bail on the thread and condescend on me once before.

[Guest]

I'm not sure that I understand the aversion to plugins. That is how Photoshop works. Yes, it would be nice if Photoshop by default shipped with such a plugin. You could make a request on Adobe's feature request page.

There are several free third-party plugins that do this and a previous discussion here pointed to a ready-made action. It should not be much trouble for Adobe to make an easy-to-use interface for a series of functions that Photoshop has had for years. Perhaps they could follow the example set by GIMP's 'Color to alpha' function.

[jyeager11]

Hi Marian,

A color-to-alpha option would be awesome indeed.

How would YOU go about manually knocking out a solid background color, without using the wand? Is there a way to do it in less than 20 steps?

(Keeping in mind, we want the background color that bleeds into the main subject on its outer edges to be knocked out too, while leaving in whatever other colors exist in those pixels. So blonde hair anti-aliasing to a blue background would simply become semi-transparent blonde fading to 100% transparent bg.)

Everyone keeps saying how it's do-able, but no one's saying how.

And I agree, not every little option needs to be included in Photoshop. But I don't consider anything that facilitates cutting out subjects with all alpha edges intact, and ready to be superposed on any background, "little". Anymore than being able to quickly modify the hue of an image can be considered a "little" option.

[Noel Carboni]

mjyeager wrote:

Keeping in mind, we want the background color that bleeds into the main subject on its outer edges to be knocked out too, while leaving in whatever other colors exist in those pixels

Well, that's the trick, isn't it?

Something so easy to describe in human terms is not at all easy to do.  While your brain might be able to discern the difference between a reflected highlight on a strand of hair and the color around the edge, that's not nearly as easy to do in software, though Photoshop CS5's new selection refinement tools are definitely more advanced than those in its predecessors.

You're saying this plug-in you once used did it without much work?  Got any results to show?

-Noel

[jyeager11]

Noel Carboni wrote:

You're saying this plug-in you once used did it without much work?  Got any results to show?

-Noel

Cybia Alphaworks, though it only does it with black and white. Enjoy the demo.

[jyeager11]

Noel Carboni wrote:

function(){return A.apply(null,[this].concat($A(arguments)))}

mjyeager wrote:

Keeping in mind, we want the background color that bleeds into the main subject on its outer edges to be knocked out too, while leaving in whatever other colors exist in those pixels

Well, that's the trick, isn't it?

Something so easy to describe in human terms is not at all easy to do.  While your brain might be able to discern the difference between a reflected highlight on a strand of hair and the color around the edge, that's not nearly as easy to do in software, though Photoshop CS5's new selection refinement tools are definitely more advanced than those in its predecessors.

I'm saying the video industry has been doing it automatically for decades... why can't we do it automatically with still frames? Video is made up of still frames!

Ever see a "making of" video of your favorite movie? Ever see actors acting in front of a green screen? That screen later gets replaced by a space station. Or a lava pit. Or whatever the director wants.

You really think they knock out the green manually using a goddamn WAND on 28 separate frames per second?

No, they have an option that knocks out the green AUTOMATICALLY, and handles all the calculations from motion blur to half-transparent dresses... whatever had green in it, will have the background video. If there's only 50% green, then you only see the background video 50% opaque.

Why is everyone acting like this is black magic or medieval sorcery?

How are video editors doing it with thousands of frames, but we're still asked to use a wand and masks and do it manually?

[Guest]

mjyeager wrote:

...You really think they knock out the green manually using a ******* WAND on 28 separate frames per second?...

Actually, in some cases, they sort of do that. That's why they call them 'matte/rotoscope/composite artists' in the film credits. You don't need to credit a ******* machine.We've gained a lot of neat toys in the past few years but it often takes a human element to determine which part of an image gets a soft mask and which gets a hard mask.

(I typed my own asterisks but they may have been automatically inserted for mjyeager)

The tone of this thread got skewed a bit in early responses. Not everyone is acting like this is an absurd feature.

[Chris Cox]

I'm saying the video industry has been doing it automatically for decades... why can't we do it automatically with still frames?

No, they've been doing something similar to extract or quick select - and then add some motion tracking to carry results forward a few frames.

Some have "automatic" modes, that end up looking like your nightly weather report (bad).

But most movies need a lot of retouching to do accurate matting (green/blue screen extraction).

Aka: video editors do pretty much the same thing that you are doing.

No, they have an option that knocks out the green AUTOMATICALLY, and handles all the calculations from motion blur to half-transparent dresses... whatever had green in it, will have the background video. If there's only 50% green, then you only see the background video 50% opaque.

That won't even come close to achieving the result you desire.  Any hint of green would become transparent -- including reflections, diffuse reflection, any green items in the foreground, things that are even sorta close to green, etc.   What you are describing is the most basic approach that everyone tries in their image processing class, then goes off to learn more because the results are so horrible.

Google "chroma key algorithm" for more info.  The Primatte article on wikipedia is a good start, and shows how even simple results aren't that simple to achieve.

[Noel Carboni]

Use just the magic wand on a high resolution image, delete, then downsize the image to the low resolutions used by television.  You will have results that will easily beat what is seen on the TV weather.  You can't even see the individual strands of the blonde's hair on TV - even HDTV.

"Green screen" work is arguably not mainstream stuff, though as I mentioned lots of people have to cut things out of images and paste them into other images.  Generalizing that job is no small task, and it sounds as though you may be condemning Photoshop without exploring the depths of its current features for doing it.

If there are current 3rd party plug-ins that do the job nicely then why not just get one?  The pretense of your original post was that something old was no longer available.

-Noel

[ScreenNameThatIsAvailable]

As a regular GIMP user who recently purchased Adobe Photoshop, I am also missing the "Color to alpha" feature!  That is the only reason why I am still using GIMP, but I would like to do ALL my editing in Photoshop so that I do not have to import/export/copy/paste back and for between the two applications.

For some reason the Photoshop people does not understand that what we need is a way to change a color e.g. green to transparent so that some shades/pixels of green would turn fully transparent and other shades of green which is darker/lighter than the selected green would turn semi-transparent.  This would keep the anti-aliasing effect and even allow semi-transparent object like windows or even hair to display realistically on the new background.

I went through hunderds of tutorials and Google searches and I could not find any way to do this in Photoshop that can do this simple task.  This is possible in the open source GIMP with only two steps.  Why can't a supposedly proper commercial product like Adobe Photoshop do such a simple task or am I missing something?

[c.pfaffenbichler]

I am not familiar with Gimp, but I may be misunderstanding you anyway – loading the color as a Selection and using it as an (inverted) Layer Mask is not what you are looking for?

[ScreenNameThatIsAvailable]

Just after I made my post I discovered this video tutorial: http://av.adobe.com/russellbrown/GreenScreenPaint_SM.mov  This is not as quick and easy as the Gimp method, but it does more or less the same job and even allow more control. 

Most other tutorials the people simply delete the transparent pixels which is not what I want. I want to keep them but in a semi-transparent state.  As a new Photoshop user I was not aware of the power of the Layer Mask.  Will look it to that.

[jyeager11]

c.pfaffenbichler wrote:

I am not familiar with Gimp, but I may be misunderstanding you anyway – loading the color as a Selection and using it as an (inverted) Layer Mask is not what you are looking for?

Try to imagine a photograph of a shadow on a flat surface.

You want the shadow, but you don't want the flat surface. How do you extrude the shadow?

Using your method, if I were to load a color as a selection, it would be the same as using the magic wand. I could grab the shadow and place it on another surface, but the shadow would retain all of the color of the previous surface. If the floor was green, then the shadow will have infinite amounts of green in it (because a shadow is not 100% opaque, it's millions of levels of transparency).

If, instead, there was a way to knock out the green from the shadow and only retain the "black" values, you could grab the shadow on the green surface and paste it on a red surface.

Same goes for heads with wild strands of hair. If the head is up against a blue background - and worse, if the hair is a little out of focus - capturing this head and moving it onto another background is hell. It's always been hell, and it continues to be hell even in CS5.

However, if you could tell Photoshop "Knock out the color I am about to select with the eye dropper tool", then that blue sky disappears, but every strand of hair remains. Even the fact that said hair is blurry will remain unaffected. Because each pixel's alpha value would depend on how much of that color was in it.

The idea is to tell Photoshop "Whatever percentage of this color is found in this pixel, make this pixel transparent to that precise amount."

Therefore, if a pixel has 20% of a given shade of blue in it, then the blue is wiped out and the pixel becomes 20% transparent. You can then place this head of hair on a yellow background. The 20% of transparency will be filled up with yellow (instead of the previous blue).

Not sure if I'm explaining it right but it's really quite simple in my head. lol

[Noel Carboni]

You've seen this video, right?

http://tv.adobe.com/watch/adobe-evangelists-russell-brown/masking-basics-in-photoshop-cs5/

-Noel