Photoshop contour effect, how to achieve this in Photoshop ? Sadly, there is no contour tool but you can create a result by using the presets and the best one is probably the outer glow feature. You can set this up by using styles
A good way, and there are always many ways to do this, is to use the outer glow style and that is to use a shape layer or image and then use the layer menu and layer styles and outer glow and set the opacity to 100% and set the blending mode to normal not the default screen etc. Set the elements technique to precise though it could be softer, it just won't follow the shape. Set the spread and size as required though probably works best if the spread is 0 and size is large. You can rapidly change the resulting response by using the contour setting in the quality and there are a number of preset to choose from and they will vary the result of the gradient stops in the outer glows. The key thing is to create a gradient with many stops. If you have a gradient with two stops then the design will not look great
You can create a preset using the editor by clicking on the preset and then adding additional stops to the bar. You can add black and white and black and white alternating or perhaps red green blue and red green blue etc alternating and so on. As long as you create a lot of stops then you will get a better offset effect with this
You can always turn the shape into a smart object with the effect added and then add another one to double up the design. Go to the layer menu and smart objects and convert and now go back to the layer menu and layer style and outer glow and add a new one
You can modify the underlying gradient but if you don't want to do that you can always simply add an adjustment / adjustment layer to the design and re-color it though it will also change the shape as well, though the shape can also be modified back to the original color as well via the fill setting for the shape
You can use the above with shapes and you can also use it with type. Set technique to precise and set the spread to 0 and then set the size and vary the contour used. If you are using Illustrator / AG Offset, you can create even more amazing offsets
If you are using creative cloud then you can use Illustrator and you create similar designs using the live offset feature. If you have the Astute Graphic's plugins then you can use the AG Offset plugin to create amazing offset designs in vector format and these artworks can also be copied to the library or just copy and paste them into the the raster application and use as pixels or smart objects etc. Even better when combined with Randomino to randomize the colors and stroke widths etc