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How do you make the circular knobs shown at the right? When zoomed in enough, there will be a fine texture of concentric circles. I only use Photoshop and Illustrator.

enter image description here

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3 Answers

up vote 6 down vote accepted

Here's a Photoshop answer. You'll have to do some experimenting with your particular image size, to avoid moire patterns, but the steps are these:

Step 1: Create a new 8x8 document @ 300 ppi

Step 2: Select a mid-gray foreground color (#808080)

Step 3: On a new blank layer, set the Shape tool to Line, its mode to Pixels, and draw a horizontal line 5 pixels thick, near the top of the image, running most of the way across. Hold Shift to constrain to horizontal.

Step 4: Ctrl/Cmd-click on the new layer thumbnail to select the line.

Step 5: Hold down Alt (Option on Mac) and with the mouse choose Edit > Free Transform. [Note: This and the Selection step ensure the transform will create a copy and will keep it on the same layer.]

Step 6: Nudge the line down by pressing Shift-down-arrow 5 times, the press Enter/Return to lock in the transformation. DON'T DESELECT.

Step 7: Press Ctl-Alt-Shft-T (Cmd-Opt-Shift-T) multiple times until you have mostly filled the layer with ridiculously thin gray lines. Now you can deselect. At full scale, it will look something like this:

gray lines

Step 8: Copy the layer and hide the original (just in case). Make a circular selection (Shift to constrain) on the copy layer that takes in roughly 50% of the layer. This is a starting point for experimentation. You may end up using a larger or smaller selection, depending on how this works for your project.

Step 9: Choose Filter > Distort > Polar Coordinates and select "Rectangular to Polar". Click OK. DON'T DESELECT.

Step 10: Create a new, blank layer below the Layer 1 copy layer. Fill the selection with a light gray (#cccccc). DON'T DESELECT.

Step 11: Target "Layer 1 copy" once again, and cut the circular section to a new layer using Ctl/Cmd-Shift-J. Trash the Layer 1 copy layer, since we're done with that. You should have something that looks roughly like this (but a lot larger):

knob face in embryo

Step 12: We'll add both bevel and gradient overlay to the circular lines. The bevel is unusual:

outer bevel

Now the Gradient Overlay using the Angle setting and a custom gradient (adjust the Angle setting to change where the highlight falls in the circle):

gradient overlay dialog

custom gradient

Step 13: Alt/Option-drag the effects to the solid gray circle layer underneath. Change the blend mode of the Gradient Overlay to Screen and the opacity to about 50%. Change the Outer Bevel to something like these settings:

knob outer bevel

This gives a final appearance like this (notes after the image):

finished knob

NOTES: A. Change the gray values to make the knob darker or lighter.

B. I found when experimenting with this that a line width of less than 5 pixels gives bad moire artifacts and aliasing when using the R->P filter.

C. Additional highlight/shadow effects like the ones in your sample are a matter of messing with the custom gradient. Just be sure that it begins and ends with the same color, or you'll see a sharp line where the two ends meet.

D. A larger circular selection will give you "grooves" that appear closer together.

E. To give the appearance of ridges, rather than grooves, reverse the grays (lighter for the lines, darker for the solid background).

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+1 this is simply Great........ –  Jack Jul 25 '11 at 9:52
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Good gravy, Alan, you are amazing! I wish I could +10 that just for all the effort you put into typing. :) –  Lauren Ipsum Jul 25 '11 at 11:35
    
LOL! Thanks, Lauren. Actually it was an interesting exercise. One of those things that makes you go, "Hmm. I wonder how I would tackle that?" The key is the Rectangular to Polar conversion. There are lots of starting points, depending on the texture you want to end up with, but it's that R->P trick that gets you there. For a fun variation, try making the lined vertical instead of horizontal. TOTALLY different result! –  Alan Gilbertson Jul 25 '11 at 20:48
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wow Alan already did a great job...

but as always :D i could have posted some screens and detailed post but i found this tutorial somewhere, so it could be easy for you to follow and do the needful.you can change colors on the fly just follow one of this tutorial.

  1. on off button texture is similar to your radio knob
  2. Stereo knob
  3. Creating a Knob in Photoshop (Video)

Download :

you can download very sleek and professional looking radio knob, every layer style and the way its summing up to the output, easily you'll understand that whats going on so take a look.

enter image description here

Hope this will help you a bit........

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I'm afraid I don't know the steps in Illustrator, but I've done this in InkScape before, which generates an SVG file which you might be able to import into Illustrator and dissect it to see the parts. (Here's the SVG file).

What I can show here is the parts that you can create it from:

1) A grey disc background

2) A series of concentric rings at about 15% transparency - see further below, but here they are shown with partial black and partial white background so you can see the relative contrast

3) A set of pairs of blurred sections of circles with 50% transparency. Each section has either a gradient fill from white at the middle to transparent just outside the edge, or the other way around.

Parts are shown here against a black background:

enter image description here

A closer look at the concentric rings They are made up of a series of pairs of rings. Each pair has one white circle and one black circle offset slight to look like a raised circular ridge. Each concentric ring is scaled from the next, scaling the width of the black and white lines at the same time.

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Put them all together and you get the following - shown at different scales.

enter image description here

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Add another disc behind with a gradient from light grey at top left to dark grey at bottom right, and you get the final button:

enter image description here

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Lovely bit of work, Roger. It would go pretty much the same way in AI. I like the "scaled engraving" effect. –  Alan Gilbertson Jul 25 '11 at 20:52
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