With these guides im trying to teach a few aspects of the program without boring everyone to tears, and today im going to tackle something which everyone will enjoy. Isolating parts of an image.

Wow, that sounds exciting, right? Well give me a minute to explain. How many times has someone in your family asked you if you can alter an image for them, either for serious use or a practical joke?

Over the years i have worked with many people either at beginner or intermediate level and it is always an interesting process to see how they approach this. the most common would be the "lasso" tool which requires very little knowledge and under certain situations can be effective. it certainly would not be a tool I would use at all in my work but a simple explanation of this very basic method can get most people selecting parts of an image.

For the purposes of this first section im going to need a picture of a face, so after a quick search on google for "weird guy" I found this site which seemed to be what I was after. Hopefully the guy wont mind us using one of his photographs but as he looks to have a wacky sense of humour im sure he won't.

Firstly open the image (bit of a no brainer). Now once we have the image opened, we need to select the lasso tool. If you dont know were the lasso tool is then follow the image to see where I have the mouse, and dont worry no one can see you being lame.

Now we have the tool selected. roughly drag a selection around his head and hair in a "ball" shape. Don't worry it does not need to be that accurate. Ill be leaving the accurate lesson for later but we will be using a different tool for that.

Now we have his head and substantial hair selected, we are going to soften the area a little so it wont be such an abrupt transition across the pixels. So now we need to head into Select/Feather.

In here you can enter anything you like, but lets keep it between 5 and 10. Now we are going to apply a filter. Filter/distort/pinch.

Here we are going to give the guy a ball shaped head, so move the slider to the left until you see the vector overlay (wire shaped diagram) on the right side of the popup panel change shape to suit. You can also copy the settings i used, and the more alert amongst you will see that you can in fact put the guy on a severe diet by moving the slider to the right. Next time your girlfriend asks you "hey does my ass look big in this?", take a picture of her, play with this technique and print it off. She will never ask again, trust me.

It is hardly art, but it can in other circumstances be a useful tool to alter the axis shape of a selected area. This leads me onto the fun part and something which I always try and teach people who are learning to select specific areas of an image. Bezier curves. Eh? what on earth are bezier curves I hear you ask.

A Bezier curve in its most common form is a simple cubic equation that can be used in any number of useful ways. Originally developed by Pierre Bézier in the 1970's for CAD/CAM operations, it became the underpinnings of the entire Adobe PostScript drawing model. Ok, that sounds extremely boring and technical but there is simply no more useful a tool in photoshop than bezier curves. Or as they are known in photoshop, "paths". Forget the lasso, marque tools and even under most circumstances forget masking, once you crack the use of the path tools, the world is your oyster. Well ok, just Photoshop.

Well I think thats enough afro's for one lesson, so for the next image and our introduction to Photoshop's paths, ive snagged an image from www.freewindows.dk

I'm sure you will agree it is a great composition from an unknown photographer. Before you ask, no they don't look real to me either but it will work well in this lesson. Who said this would be boring?

Open the image and select the path tool on the toolbar to the left in this image (marked 1.). Note all the red areas and make sure they are marked accordingly. In the red area marked (2) Adobe Photoshop defaults to "shape layers" which will seriously hamper this lesson unless you make sure it is in the middle area (hover over it and it will say "paths". When you have it correctly highlighted it will be pressed down. Our final tip and requirement for this lesson is in the red area marked (3). The "rubber band" - This is a great tool to leave on when using paths in Photoshop, as it will guide you around your selection. More on that in a minute.

Before we progress any further, here are some handy quickeys that should become a part of your photoshop repertoire, so memorise them (if you dont already know).

CNTL and + = Zoom in.
CNTL and - = Zoom out.
SPACE = Hold the image with your "hand" - click left mouse button (great for moving).

Some other useful quickkeys. control D for deselecting a selection. control H for "hiding" a selection on screen so you can see the image clearly.

Let us try these out first, hit control and the plus key (next to backspace) to zoom into 200% on the image.

Notice the 200% highlighted in the image window - you can go right into 1600% for very fine and accurate work, useful sometimes but not really needed with this - 100% is the actual size for webwork. This may seem simple in theory but many photoshop users do not know any of the keys, and they REALLY speed up the operation of the program. Remember above i mentioned the use of the SPACE bar? try holding it down when zoomed in (and you have scrollbars on the image). Now click on the image with the left mouse button and move the mouse. Hey presto, the image will move with your mouse. This simple technique proves exceptionally useful as you begin to use the path tool on large images which will not fit on your monitor zoomed in. Not working for you? Then make sure the image window is highlighted if not in maximise mode, and make sure the space bar is kept down at all times. The mouse pointer will change to a little white hand.

Ok now that you have got a hang of using the CNTL - plus and minus keys and the spacebar, we can move onto some selections.

With the image at 200% or 300% select the path tool and click on the left side of the image, right on the girl's knuckle as shown in the image above with the red highlight. Once you click this you will notice the "rubber band" option we toggled on earlier coming into play, it is showing you now where the path will continue when you NEXT click. right now we are going to keep it simple with straight paths, so for the next stage click on the joint of her wrist.

I will not continue with every individual step but follow a quick trace part way up the girls arm.

We are basically "tracing" the path up the girls arm, manually. I have shown in red outlines the clicks I used to do this. You dont need to follow my clicks exactly. Right now we are keeping it simple, with straight lines in the path, so follow the arm trace as shown.

It is time to "close" this path, by returning to the start, that being the position we first started this path.

So now we are returning to the beginning and following the arm from the other side back to our starting point. When you "hover" the path pointer over the starting point you will see a "0" beside the pointer. This is Photoshop's way of telling you that you will close (end) the path by clicking this point.

So now we have our first, simple and straight line path. Congratulations.

If you dont already have the paths floating palette open, go to window/paths and it will appear on screen. You will see it highlighted in the image above with a red outline. Click the little arrow on the right hand side of this pallette and go into palette options.

In here you can change the sizing of the paths preview icon in the path's palette. Depending on your resolution and eyesight you can tailor this to your individual needs, but the medium/middle setting seems to work well for most people.

Now we want to store our path, so double click on the "work path" and then rename it to "arm outline" see the red outlines in the image below for help with this if you get lost.

Path options are very cool, they remain in your image to work with later, even if you save the file as a jpeg! Don't believe me ? Resave the image now with your stored path, and reopen it. you are beginning to see the versatility and power that path's can bring to your images.

Ok, so now we have this path, what on earth can we do with it ? Basically what we have told photoshop via its WYSIWYG interface is that we may want this area isolated for removal, alteration or pasting into another image. Obviously half of an arm isn't much good to anyone but the principal is the same for everything you trace around with a path. Another added benefit of this technique is that if you resize the image, the path resizes with it to remain in scale with the image.

So now we want to turn this path into a selection, go back into the little arrow on the right top side of the path palette and click "make selection". the image below will guide you.

If this does NOT work for you, then make sure you click once on the "arm outline" thumbnail in the palette to highlight it (make it active).

Now we want to make the path an active selection with the parameters used above. You are free to experiment with feathering techniques, some of which hopefully have stayed with you from our prior lesson. a figure of 2 gives a slightly soft edge.

Open the image above. No 2 shows the mover tool, click it and move the highlighted arm. incidentally some people call the selection or highlight "marching ants" but I think that term is rather dumb. Let's just call it a selection.

So can anyone tell me which of these items in red highlight are related? Yes, you guessed it, when we moved the arm No4. we left the background colour in position 3. If you look at the area on the left ive highlighted (no.1), this is the foreground and background colour. The blue in the image is the background colour and the red is the foreground colour. So to sum up, we moved the selected arm with the mover tool, when it was moved, it left the background colour of blue in it's place. We can easily change the foreground or background colour by clicking on the respective area within No1 selection.

So there you go, that is your first selection with the path tool. Obviously most tasks wont require all straight lines so now we are moving into the more complex area of curving path selections.


Open the image of the lovely lady again and zoom into 500%. Yes, use the quickkey commands you learned earlier. You did learn them right? tsk tsk. Here is a reminder:

CNTL and + = Zoom in.
CNTL and - = Zoom out.
SPACE = Hold the image with your "hand" - click left mouse button (great for moving).

Click again on the point just at her knuckle. release without moving.

This is where we mix it up a little, her arm isnt perfectly straight, and regardless of how many people say the lasso tool "rocks", it has limitations, some of which i have mentioned earlier, and some of which you would find out if you tried to manually trace the image of this girl. Your hand will never get it pixel perfect, and with path experience you will be able to achieve this, easily.

So we have our first point as shown above, but this time when you click the next point dont let go of the left mouse button, instead follow the shape of her wrist upwards slightly to "bend" the path, and then let go.

Do not get annoyed if you cannot master this first time, it comes with experience.

Above is a simple diagram to show you how it is done in Photoshop. I have also included a flash video wihch you can watch. I used Snagit to record this on my Dell 2405, so its at 1920x1200. you can watch this over here and would be ideal for viewing (just scroll if you resolution is lower). however if this is too irritating for you, ive scaled the flash to 1024 over here, but it might be hard to see what im doing. When you have watched this demonstration just close the window and come back here. The path I made is not pixel perfect but due to the file size I rushed the creation somewhat. Nonetheless it should give you a much better indication of when and how to bend the path around an image.

This will give you a good indication of how it is done. Watch the mouse pointer change icon when the path is being created. When it changes into a small black arrow icon this is when im clicking down and dragging the path to follow the curvature of the womans body shape. When im scrolling, im doing so on the fly via the SPACE bar, meaning I dont lose track of the path i'm creating.

Be aware that you do not want to drag the line too far on each point as the reverse will apply "behind" the point - remember you are following the curvature of an image, you do not want to go overboard when pulling the path in a direction. This is a very hard aspect of path creation to explain in mere text, again I would urge you to watch the video.

The path tool has various sections to it. if you hold down the button over the path tool as shown in the image above. you will see other options (subsections) to this tool. They are:

Freeform pen tool - for freehand drawing, does exactly what it says on the tin.
Add anchor point tool - for adding points into a path you have or are creating.
Delete anchor point tool - for removing points into a path you have or are creating.
Convert point tool - for converting a path point from a straight line intersection to a curved one.

You may find the delete and add anchor point useful if you make errors in your path creation, and are really straightforward to use.

As you will have realised by now to perfectly isolate the lady from the background you will need more than one path as we will not want the areas of sea and sand between her arms and the garment she is wearing. The image above shows the flow you will take on the 4 path sections to create the isolation. It is really simple.

Click on the image above to get the full sized image, then save to desktop and open in photoshop. You will see a finished path cutout around the girl, something like this should be your end result. As I mentioned earlier Photoshop is clever when resizing with a path on the image, the more diligent amongst you might already have noticed that the thumbnail image above has the path also embedded into the jpeg. Right click the thumbnail and save as to your desktop and open in photoshop. Nifty.

Now we want to copy the girl into another canvas, so with the information I showed you earlier, highlight the path, make a 2pixel feather selection. Press Control C to copy into the clipboard. then press Control N for a new canvas, make the new canvas have a black background. You will have noticed that Photoshop has sensed the size of the image in the clipboard and will make the canvas match. Press return to exit the dialogue and Control v to paste the image into the new canvas.

Due to the 2px feathering we applied you can see the edges are not sharp. You can experiment with this in the prior steps and see how your cutout looks when pasted onto another image, not just a plain black background.

So there you go, hopefully by now you will be more familar with paths, selections and manipulating images. Be prepared, because the next time we delve into paths it will be a lot more complex.


I'll sign off this time with a note to those benchmarkers amongst you to try our Photoshop bench, It is a great real world stress test for your system.



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