CraigPJ's blog

A Quick Method for Isolating Objects on White

posted by CraigPJ, Jan 26, 2008 4:03 AM — 31 comments

This tutorial was performed in Photoshop CS3, but the same can be achieved in older PS version and probably Paintshop Pro or other apps that support layers.

A prerequisite for using this method (which I discovered through trial and error), is that the object should be photographed on a fairly clean bright background. The closer to white, or the brighter the better. When I use this method I usually shoot the objects using a $20 light tent bought on ebay. My setup looks as follows:



(more photos and descriptions can be seen here: here)

Bear in mind that this equipment is not essential. Previously I used to make do with a white bed sheet draped over an upside-down coffee table, and some bright spotlights shining on the sheet. Inside I have a large sheet of white cardboard forming a ramp towards the back (so that there was no “horizon”). Take a few test photos of the background (it doesn’t need to be in focus) and adjust the white balance of your camera until it looks as neutral (no colour cast) as possible. I have the white balance from my light tent setup stored as a preset in my camera.

When I take the object shot I usually try to adjust the exposure so that the white background is as close to white as possible, without getting highlight clipping (when the histogram in the camera or Photo application goes off the right hand side of the scale)

Starting the isolation (Clicking on Any Image will take you to a larger version)

With a little luck and patience, you will get an object shot looking like this:



Although Mr Beetle’s background is fairly clean, it is not pure white (same colour as the page), and there are a few dirty spots (added for this demo).

Open the photo in Photoshop (“PS”)

Press F7 to go to the Layers Palette (or select it manually). Double Click the “Background” layer, and if you want, you can rename it to Object.



Right Click in the Blank area of the Layer (blue in my case) and select Duplicate Layer.



Click Image/Adjustments/Threshold on the menus. Drag the slider to the left until most of you object (and its shadow if required) is totally black and as little background as possible is black. Take note of the “Threshold Level” (226 in the case of Mr Beetle). Press Cancel (not OK!).



Make sure the topmost layer is selected and click Select/Color Range. In the “Select” dropdown, choose “Highlights” and press OK



Make sure the topmost layer is selected and click the “Add Layer Mask” button in the Layers Palette



Open the Channels Palette and Select the Layer Mask. Make the colour channels invisible by clicking the eye beside the RGB channel Make the layer mask visible by clicking the empty box beside the Mask layer until the eye appears.



Set the background colour to black and zoom into your object so that it fills the screen.



Choose the “Eraser” tool and set the brush size to an appropriate size and change the hardness to 100%. Look for any non-black (white or grey) areas in the main body of your object and “Erase” them to black. Don’t worry about the shadow areas.



Change the Background colour to white and erase any dirty (non-white) spots on you background. Again, don’t worry about the shadow areas. I find that this works well with a large brush. I usually do most of the background area without touching the object, just to make sure that the background is perfectly clean (sometimes it can be difficult to see tiny grey spots in the background area of the mask.



Unhide the RGB channel and Hide the Mask Channel, then go back to the Layers Palette.

Select the topmost layer, and make sure you select the image, not the mask within the layer.

Click Image/Adjustments/Levels or press CTRL-L. Enter the Threshold Level that you obtained earlier in the box below the top white slider (default is 255).



The Background should now appear as pure white, except for any dirty spots on the background. Select the eyedropper tool and right-click anywhere in you image. Select “Point Sample”.



Select the Brush tool and choose pure white as the foreground colour. I like to set the hardness to 100% and the brush size to quite large for this bit. Paint out any imperfections on the background. I usually give the whole background a once-over to make it perfectly white. This is usually quite easy and I find this can usually be done fairly roughly. If you want to be thorough you can switch on the Info Palette, and move the brush around the white background. Whenever the R, G and B values are not all 255, paint it out (with a large hard brush to be sure). Take care to make sure the edges of the images are perfectly white. These are the easiest to spot if not done properly. After not too long, you would have removed all unsightly spots.



Now you should have a nice white background. Select the Layer Mask of the Top most layer.



Select Filter/Blur/Gaussian Blur. The value you choose will determine how smooth the intersection is between the background (top layer), and your object showing through a transparent hole in the top layer. If you have trouble understanding what is happening here, hide and unhide each layer to see what parts of the combined image are coming from each layer. For the Gaussian Blur value, I usually use between 50-100, but very occasionally as high as 250 (max). It’s a matter of personal taste.



The isolation is now complete, but if you want, you can select the bottom layer, and adjust things like levels, curves, colour balance, contrast etc, without affecting the background.

Removing Texture from the shadow

Although this is not strictly speaking part of the isolation, I find it a useful trick sometimes. If you are observant, you may have noticed that there is a fabric texture visible in the Beetle's shadow. This is the texture of the nylon fabric that I shot the shot on. You will find that even if you shoot on a piece of clean white paper and if the photo is sharp, the texture will be visible in the shadows after you have performed the isolation. This is a method that I put together (again probably not original)to fix this.

Once the image is isolated, flatten it to a single layer. choose the Magic wand tool and set the tolerance to between 10 and 20 (I find this range works well) and set the Selection method to "Add to Selection". It should then be quite easy to select the shadow area on the background as well as the white background without selecting the object. Adjust the tolerance if necessary and subtract bits of the object if they get selected (see image below). You don't need to be excruciatingly accurate with the selection, because you will blur the selection.

Once you are happy that you have the background including the shadows selected, go to the Channels palette and click the "Save Selection as Channel" button (see below).



The New Channel will be called "Alpha 1". Hide all of the channels except "Alpha 1" (click the eye), and make "Alpha 1" visible. Select "Alpha 1" and click Filter/Blur/Gaussian Blur. Set the radius to 2 (I actually find that anything between 1.3 and 2 works well). This will blur Alpha 1.



Now hide "Alpha 1" and unhide RGB (which will unhide R, G and B). Make sure that you also select the RGB Channel.

Click Filter/Blur/Lens Blur. Under Depth Map, select "Alpha 1" as the source. I just use the default settings (but you could experiment). This will smooth out the textured shadow without affecting the Object



The result of using the above two methods can be seen here http://www.sxc.hu/photo/930508 (Feel free to download the full sized version :)

A few more examples of using this method can be seen here:




Hope you found this tutorial useful.

Cheers
Craig


Comments | RSS

1. posted by aj21, Jan 22, 2009 6:11 PM

Not a method I have used myself, I tend to go for the tidy up the image and then make a path using the pen tool method......very useful I shall try that one!

thanks


2. posted by crprinting, Jan 12, 2010 3:24 AM

I wish i'd found SXC blogs sooner.. there's some awesome posts on here.

very nice tutorial thanks mate for sharing


3. posted by Slantsixx, Jan 26, 2008 7:07 PM

Thanks or this tutorial!


4. posted by bosela, Jan 27, 2008 6:04 PM

Thanks for putting this together.

Why doesn't this blog is show up in the community blog page:

http://www.sxc.hu/blog

It seems like it should appear there as one of the most recent blogs?


5. posted by crisderaud, Jan 27, 2008 10:16 PM

Good tutorial Craig. Thanks for puting it together.


6. posted by CraigPJ, Jan 28, 2008 7:50 AM

Thanks all:


@2 I'm not sure why. I did mark it as "Suggest for front page", last time I did that it did take the post a few weeks to appear on the front page.


7. posted by Slantsixx, Jan 30, 2008 4:58 AM

It's not a blog, it's a tutorial ;)

Check here: http://www.sxc.hu/tutorials


8. posted by CraigPJ, Jan 30, 2008 6:53 AM

I Know, but as far as I know, tutorials can also appear on the front page. I have seen it under the tutorials already.


9. posted by scol22, Feb 10, 2008 9:30 PM

Thank you Craig!
I just practiced isolating a few objects, by following your instructions.
Yours is a little different than my usual "isolation" routine and i learned a few new tricks that i'm sure will be very useful in the future.
Thanks a lot for sharing your secrets!!!


10. posted by CraigPJ, Feb 11, 2008 12:19 AM

@7 No probs. As I said it is more or less cobbled together, and it is not suitable for all isolation. I find that it sometimes takes a bit of experimentation to get it perfect.

For situations where I don't want to keep the shadow, I almost always use the clipping path (using the pen tool) method.


11. posted by lorddevil, Feb 11, 2008 10:11 PM

very nice tutorial thanks mate for sharing


12. posted by sam_905, Feb 21, 2008 5:15 PM

Craig, a nice tutorial. I have a couple of questions. Looking at the picture of your set up I'm trying to figure out where the upside down coffee table is. May be it's the relative scale that throws me off. Also it looks like you use a flash. And do you use just regular incandescent light bulbs? Thanks


13. posted by CraigPJ, Feb 21, 2008 10:32 PM

Thanks Sam.

The upside down coffee table was part of my old setup before I got the light tent. I used to drape a white bedsheet over it as a makeshift light tent. I used the legs to support a piece of curved white cardboard to create a ramp-like backdrop. It's a bit difficult to explain, but I will try and take a photo of it when I get a chance.

I usually use three 500W halogen spots from the top to provide lighting. Recently however, I have been experimenting with using a wireless flash with a stofen diffuser pointed at the light tent. That works really nicely for providing directional light. My recent caterpillar series was taken using the flash in the light tent with a black backdrop.
http://www.sxc.hu/browse.phtml?f=advanced_search&q- 1=caterpillar&q2=isolated&q3=&cat=0&r=3&xsize=0&ys- ize=0&by=CraigPJ&d2=2008-02-21&d1=2001-01-01&t=3&x- =0&y=0


14. posted by CraigPJ, Feb 21, 2008 10:33 PM

Sam: More photos of my setup can be seen here: http://www.flickr.com/photos/craigjewell/sets/7215- 7603169049005/


15. posted by sam_905, Feb 22, 2008 1:18 AM

Thanks, Craig. I am thinking of something like this on a shoestring budget. I've been dabbling in stock photography but lighting proved to be a chalenge. I found that a wireless flash works well but I really need to get rid of shadows and reflections. It is also hard to make lighting uniform without a light tent. I do mostly street and people photography so I've got to make a mental switch when I shoot stock


16. posted by sofijab, Mar 26, 2008 4:36 PM

Very useful, thanks!


17. posted by josecarli, May 31, 2008 8:42 PM

Great tutorial and excellent results. Thanks for sharing.


18. posted by dukelips, Jul 17, 2008 5:16 AM

Its slight modification from the method used by scott kelby.

The variation is the usage of white brush with overlay


19. posted by 000ps, Nov 9, 2008 10:48 PM

this is perfect


20. posted by hisho1968, Nov 25, 2008 9:07 PM

It was very useful craig, clear explanation in logic sequence through simple way, thanks a lot for sharing this with us.


21. posted by simo13, Feb 20, 2009 1:14 AM

ay bro...this is like totally radness...


22. posted by kremerb, Mar 10, 2009 10:21 PM

thanks a lot, great tutorial


23. posted by sadmaan, Jun 24, 2012 5:06 PM

This a tutorial for Adobe photoshop CS3. But I'm using CS6 at present. So I'm facing online casino games some huge problems. Can you give a link or something for Adobe CS6??


24. posted by careersB, May 27, 2013 3:56 AM

AWESOME. thank you for taking your time to teach us! I really learned a lot. WOW.


25. posted by piabpn953, Jun 21, 2013 1:56 AM

very nice tutorial thanks mate for sharing


26. posted by renderiska, Jun 21, 2013 5:56 AM

It's Very Good!


27. posted by chrissaluu, Jun 28, 2013 4:30 AM

this is perfect


28. posted by carlislekm, Jul 29, 2013 4:19 AM

Very interesting


29. posted by korinci, Aug 23, 2013 11:51 PM

Very useful, thanks!


30. posted by shannahqxh, Aug 24, 2013 6:36 AM

very nice


31. posted by inizjall, Nov 6, 2013 3:33 AM

that was worth reading.. isolation

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