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Sally Jane Photographic Art

Adobe Photoshop Tutorial


Adobe Photoshop -Filters - Extract extracting


This is a tool I love to hate. I can't do without it but it takes a lot of care and understanding to get the most out of it. Thankfully Adobe have improved it slightly in the cs3 update but it still far from perfect but then I expect a lot.

The Extract function / tool / filter or whatever you like to call it as Adobe has left that blank, lives in the Filters drop down menu since Photoshop cs. Before that it lived under Image on the menu bar. Before we get started though I suggest you prepare your image in the way I always do by duplicating it in the layers pallet and then adding a new layer in between the two which you fill with white. The image right shows you what your layers and history pallet should look like if you have them visible once you have set your image up correctly.

The image I will be working on is a photo of my walking boots. When I took the photo I intended to remove the background so I made life a little easier for myself by placing them on a white board. Unfortunately I still got some of my garden in the background and as you will see the colours of the terra cotta plant pots tends to blend in a bit with the brown leather boots. Not to worry, Extract should still be able to cope with a little TLC.

Click on the top layer in your layers pallet to make it active. In my image it is called Layer 1 because it was the first layer I created and I didn't bother to rename it. Now go to Filter on the top menu bar and select Extract from the drop down list. You will get a window come up with your image displayed in it which will look something like this.


This is from cs3 so there are a few extra features here than you would have if you are using an earlier version. The only new feature that I have found any good though, is the check box called Smart Highlighting. I'll talk about that in a minute. Basically what you do in this window is to tell Photoshop what makes up the edge of your selection and what is inside it and what is outside and can be removed. You do this by drawing a highlight line over the edge of your subject. I say over because it is important that you include a thin strip of the inside pixels and the outside pixels so the program can work out where the edge is. Once you have gone all the way around you then fill the inside with the paint bucket tool to tell the program which of those edge pixels were the good ones and which were for discarding. Everything in the middle will be kept and the program will just work on the highlighted edge pixels sorting out which meet the 'keep' criteria and which don't. If the subject contrasts well with the background as it does here for most of the image, the programs works really well but when the difference is less obvious it tends to struggle a bit and some repair work will be required.

OK so lets get started. The top tool on the left is the highlighter tool that you will use to draw around your subject. In the tool options box over on the right you can select your nib size. You want a nib that is large enough to cover the edge easily and take in some of the data from either side. If your edge is in soft focus or is fluffy you will need a larger nib than if it is sharp, smooth and well defined. Using too large a nib will mean more work later on correcting the mistakes the program will make. Remember it only works on the area under the highlighted line as everything inside will be kept and everything outside will be discarded. In cs3 there is that little check box for Smart Highlighting. This automatically shrinks the nib size to one it feels is appropriate for the edge as you go round. With this box checked you can select a larger nib than you would normally because Photoshop will reduce it to an optimum size. Now having a larger nib will actually make it easier to trace around the edge without missing it.

The other options in the tool options box allows you to select a colour for your highlighted edge and for the fill. By default the highlight is green and the fill blue but you can change these if they don't show up well in your image.

At the bottom there are two more check boxes that should be checked by default called show highlight and show fill. If they are not checked in your window click on them to check them. You can ignore the rest of the options as I personally found them to be useless.

On the left there is a magnifying glass tool. click on it and then click on your image a couple of time to enlarge it and make it easier to see the edge of your subject clearly. Now click on your highlight pen tool again and carefully work around the edge of your subject. Where the image goes out of your viewing area hold the shift bar down on your keyboard and your cursor will change to a hand. You can now drag the image to reposition it. Once you release the shift bar the cursor will revert to the pen tool. If you make a mistake with the pen tool there is an eraser tool you can use to remove it. Once you have gone all the way around the subject, click on the paint bucket tool and then click in the centre of the subject in your image. It will fill with blue or whatever colour you selected. The outside should remain unfilled but if your whole image turns blue it is because you left a gap somewhere in your highlighting. Reselect the pen tool and carefully examine the highlighted edge of your image. When you fin the gap draw over it to close it. As you do the blue will instantly disappear. Once you have fixed the breach, refill the centre with the pain bucket. If your whole image turns blue again you have another gap somewhere. Try enlarging your image a bit more and reexamine the edge until you find it. If you have successfully made your selection so only the centre is blue you are ready to go to the next step.


You may now notice the Preview button has become available on the top right. This allows you to preview what your selection will look like and fix any errors before accepting it. I used to use this feature but I have found an easier way which is why I told you to make a duplicate layer at the start. Click on OK and you will be taken back to the normal Photoshop work area. Your subject will appear minus it's background but chances are it will look a bit fuzzy around the edge.


You can't see it very well in this image because it is too small but the selection is far from perfect. We need to go around the edge repairing any missing data and removing extraneous matter. To do that we use the history brush and the eraser. You will find them both in the tools pallet. These will be used in conjunction with each other constantly alternating between the two. Set them up both the same. You want them to be quite small, for this image I will select a brush size of 9 and a semi soft edge for both. If your subject has a soft focus edge you will need to softer edge on your brush and eraser. Zoom in on your image to at least 100% or 200% if it is particularly fiddly. Now check the edge carefully remembering you only need to check the area that was originally highlighted with the pen tool. If there is any gaps or faded areas go over it with the history brush to restore it and if there is any background rubbish, switch to the eraser and remove it. Do make sure, however, that you are working on the right layer and not the middle white layer you created because you won't actually see the difference until it's too late. If you can't tell where the edge should have been you can either turn off the white layer briefly in your layers pallet or reduce the opacity so you can see the original image.


The image above shows the area where the boot's edge was a bit fluffy and where the background was similar in colour. You can see here were there is missing data and some extraneous matter. Below is the same view with the white layer turned off so you can see the original background.


To fix this I zoomed in to 200% and reduced the size of my brushes to 3. I wanted to get all the fluffy bits from the raw edge of the leather tongue as perfectly as possible as I'm quite finicky about details like this. Often I am working with hair and this then gets very tricky so compared to that this is easy. If you are working with hair you may have to make some compromises. In the main, if teh hair contrasts well with the background the program does a pretty good job but where the background is fussy you may find you have to artifically repaint the hair or trim it back completely.


This is what it looked like once I'd tidied it up and below is the finished product. Two boots minus any background ready to be placed in another image of some kind. The bottom two layers have been turned off and can be deleted before saving. To save this image and maintain the transparent background you will need to either save it as a PSD file, a TIFF or a GIFF but in the options window make sure you select preserve transparency.


Recommended Further Reading for Photoshop

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Tel. 07956 448690

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