A quick guide to the maximum filter in Adobe Photoshop, great for spreading whites and chocking blacks and some unusual blurry effects
The maximum filter can be found in the filter command and others and maximum.
The basic point is to spread white and choke the black (according to the Adobe site) but as with many filters, it can do a lot more than that.
There are not many options though, radius and preserve (squareness and roundness). The higher the setting, the slower. the application
Personally, I always prefer the roundness option to the squareness as the results seem to be less crude.
You can use the Photoshop maximum filter with brush strokes.
1) Select the brush tool and apply brush strokes in black (using a default stroke and on a white background)
2) maximum filter and apply with a decent sized radius, though the actual results depends on the radius and what you want. If you have applied a number of brush strokes with a setting of 60px then it probably is not a good idea to set the radius to 60px as you will just end up with white.
3) Set the radius of the maximum to 15px and then re-apply a few times (filters can be applied multiple times with more subtle changes than a brutal one click effect). You will then end up with a much lighter pencil like drawing than than the original sketch, a bit like the effect of reducing a large comic page to a smaller actual comic.
You can also use the maximum filter with other filters as well as using the fade command and fading the maximum filter by using difference (to get a double line) You can find many brushes on the site such as frame embellish brushes and fleur-de-lis brushes and distressed circle brushes
You can use the Photoshop maximum filter with type to create thin black type or perhaps faded black type (or whatever color the type has been set to). Such as the type on the left where the futura PT has been reduced to the point where the ink in the typewriter is very uneven and clearly needs a new ribbon in a short while
Say you have a paragraph or page filled with type with a bold typeface, you can apply the maximum filter to that to thin the type - the actual thinning depends on the radius. You can simply flatten the type or use the type as a smart object / converted payer via the smart object command.
You can create all kinds of interesting visual effects with type by combining maximum filter and gaussian blur and maximum filter again to create type that looks as expected but certainly is not. As the type is a layer / smart object, it can be duplicated along with the smart filters and then applied on top of each other using blending modes.
If you change the color of the type to white, the result is the same with a choking of the white (which does seems odd).
You can use the Photoshop maximum filter with custom shapes to thin any of the shape designs. As the custom shape can be converted into a smart object, the maximum filter thinning can be varied. The result on the custom shapes depends on the shape, some shapes such as an Illustration / sketched shape will be reduced and parts of the illustration will just vanish.
If you are using the maximum filter with something like a circle shape then you will just see an overall reduction in the vector design. You can find many shapes on the site such as greek ornament / divider custom shapes and gear and cog custom shapes and frame and border / edge design custom shapes
You can create a layer and add a mask via the layer mask command in the layers menu. Go to the layers panel and select the layer mask (to the right of the layer) and then add some shapes in black or perhaps some brush strokes. You can then go to the filter menu and apply the maximum filter to the mask and the result will be more of the actual layer. It should be noted here that the maximum filter is destructive and is not a smart filter so any applications will change the selected artwork.
Add a shape or image or type to a document.
You can also use the maximum filter with channels.
Go to the channel panel and select the red channel and select the maximum filter in the filter menu and set the radius to 20px say, go to the green channel and then re-run the filter but this time using 10px and then the blue etc. You can re-apply the filter multiple times to the same channel.
Go back to the RGB (or CMYK etc) image.
You will now see a colorful edge around the design.
This really depends on the image, but I have always found the maximum filter with the roundness setting generates an unusual sparkly glow with highlights and gives the image a really surreal look. The squareness option for the filter is never as pleasing but it has a use in creating very large blocks of color across an image which can be blended with the original image using the fade command.
If you set the roundness / radius setting to too higher a value then the filter will be slow and will result in a totally white image but it does work well if you use an image with channels and the maximum filter and set one of the channels to a very high value.
A low value of the maximum filter often just makes a person look a little sweaty as if they are under hot lights.
The maximum filter can be used to create some interesting effects when combined with adjustment filters such as black and white to create an unusual glistening effect with people etc
The image on the right was created using multiple applications of a low setting of radius of the maximum filter in Photoshop and then adjusted using black and white adjustment mixed with hdr toning to create a slightly more surreal look
You can find many other tutorials such as
You can find more about the filter via how to use the maximum filter in Photoshop (youtube)