Simulating Materials in Photoshop

How do you project the properties of different materials in Photoshop? This tutorial takes a brief look in the techniques involved to make convincing plastic, metal and cloth. The trick to achieving this is to observe the details of the behaviour of different materials in real world situations.

The final objective of this tutorial is the inspire you to observe and recreate in Photoshop. Although this tutorial will explain in-depth the properties of a few materials and touch on the techniques involved, I hope you will take the time to do the observing yourself after this tutorial. After all, would you rather have the Midas touch, or are you content with a gold bar only?

Laying the Foundation

OK, before we start painting, we need to have a block to paint on. For this purpose, I have made a selection like the one in the image using the Pen Tool. Then, I made my Path a selection by going to the Paths tab and pressing the Load Path as Selection button. Then, I filled it with a medium grey (#d2d2d2). Oh yeah, all this happens on a new layer, I forgot to add.

Why medium grey? That's so that we have both lighter and darker hues to work with later on. You see, I am going to introduce a technique where the Burn Tool and Dodge Tool are used to shade our grey little block later on. If we used a very light or dark grey (or stupid enough to use plain white or black), we can't do much with the two tools. Don't believe me? Try it!

When I shade my blocks, I always start with grey and colorize it later, when the shading is done. That's also the same in this case. First, I determined where the light source is going to come from. Then, I use the Burn Tool to shade the areas where shadows will form (the area opposite to the light source). As a rule of thumb, I always start by shading darker areas, and leave the Dodge Tool for defining highlights.

I hope that you can follow up to now. Anyway, now that we have our basic block to experiment on, click on to the next page to start with the materials!

Material Properties

Just for this purpose, I paid a visit to my school library and found out these "properties" from a pencil sketch book:

• Metal
  • thin but strong specular highlight
  • hard and dark shadows
  • reflect the environment
• Plastic
  • specular highlight is pretty weak
  • very soft shadows
• Cloth
  • little or no specular highlight at all
  • soft shadows

From the information above, I shall discuss how I applied the knowledge (and some of my own observations) to Photoshop. Note that the properties above are only visual, I don't think they are accurate scientifically.

Metal

Let's start with metal. Still using the crude block thing that we have shaded in Photoshop just now, we shall, using the Burn Tool, darken the edges a bit. This is to achieve a "hard and dark shadow". This little technique also helps the metal block to stand out from the background, and it is necessary as well so that the next step can be applied to achieve the desired effect. Generally speaking, you should shade the parts facing the floor (downwards) darker to simulate shadows.

Then, whip out the Dodge Tool to shade some specular highlights. In plain English, a "specular highlight" is the white line of light that is reflected on metals where the surface is facing the light. For specular highlights, use a small brush (thin highlight) and strong exposure (strong highlight), around 50%. Dodge around the edges until you get something like the image.

Then, we are going to work on the "reflect the environment" property of metals. For simplicity's sake, we are going to create an illusion of the block reflecting the background, which is white. However, we shall not dodge the reflection on; instead, we will use my favourite method: curves. Go to Image > Adjustments>Curves to open the Curves dialog and use a curve like this:

I hope you can get a result like something in the image to the right. To finish the block, I used the Burn Tool to darken some of the edges that have been lightened too much by the Curves. Also, use a soft fuzzy brush to paint a shadow on a layer beneath.

Instant metal! Before we move on to the next material, I would like to remind you on a few points when doing metal blocks. Always remember to shade shadows in the right places, and always use a strong highlight. Or else, you will get a wierd effect when you apply the Curves. Also, avoid highlights that are too thick, as it takes away from the realism of the image.

Material Properties

Let's recap on our properties of plastic and cloth:

• Plastic
  • specular highlight is pretty weak
  • very soft shadows
• Cloth
  • little or no specular highlight at all
  • soft shadows

Comparing their properties, I noticed that plastic and cloths have similar properties: weak highlights and soft shadows. Therefore, let me forewarn you before we begin: don't overdo your Burning or Dodging, as this will make your thingie NOT look like what it is.

Let's start with the grey block that we began with on the first page. Plastics generally have soft hues and there is not much contrast in the colours. To achieve this, I just used Image > Adjustments > Brightness/Contrast to drop the contrast of the image by a tad bit (by 41, to be exact).

Let's continue with cloth. First, to make a piece of cloth, I used the Pen Tool to draw an outline. Remember, cloth is soft so it would be convincing if you draped your piece of cloth over a surface. As an alternative, you can also make creases in the cloth. These are for the purpose of presenting the piece of cloth as soft, which makes it convincing. You'd probably take a few tries before getting the shape right.

Then, I loaded the path into a selection and filled it a medium grey, as I said in the first page of this tutorial. Next, I used the Dodge Tool and Burn Tool to shade the cloth according the the shadows and light direction that I used in the plastic block above. Remember, do not dodge highlights or burn shadows that are too strong, as this will take away from the cloth feel. In the image, I switched off the plastic block layer so that you can view my shading better.

Now, to add creases. First, I zoomed up to the part of the cloth that I want to make creases on by pressing CTRL + + (zoom in) and CTRL + - (zoom out). Then, using the Pen Tool, I made a shape like the image and loaded it into a selection as well. Then, I filled it the same medium grey that I filled the cloth with.

Then, I burned shadows on the part of the crease where shadows will be cast (see image) and highlighted parts facing the light as well. Then, I added colour to the plastic block and cloth by choosing the appropriate layer and going to Image > Adjustments > Color Balance. In this dialogue, colours are tweaked according to their tone. You can switch between the light/dark tones by choosing the respective radio buttons under "Tone Balance".

Finally, I used a fuzzy black brush to paint shadows. Remember to paint shadows on a different layer than the objects, so that you can erase parts of the shadow that are in excess.

This is the final image I got: