A Quick Method for Isolating Objects on White by CraigPJ

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:

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

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.


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Acerca de kailep

soy kailep, tengo 21 y soy estudiante de la carrera de diseño gráfico en Morelia. Mayo 2010: soy kailep, tengo 23 y trabajo en una imprenta de Morelia. Junio 2010: soy kailep, tengo 23 y estoy estudiando en Digital Invaders. Octubre 2010: soy kailep, tengo 23 y estoy trabajando en una agencia en Saltillo. Marzo 2011: soy caleb, tengo 24 y soy Director de Arte en Monterrey. Julio 2012: soy caleb, tengo 25 y ahora soy Director Creativo en el DF Agosto 2013: soy caleb, tengo 26 y sigo de Director Creativo en el DF Septiembre 2014: soy caleb, tengo 27 y soy Director Creativo en Quito, Ecuador.

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