Advanced_Photoshop_Issue_136_-_2015_UK_.

12

PUT THE MASK TO GOOD USE

Go to the Channels tab, and click while you

hold Cmd/Ctrl pressed on the RGB Channel to select

the white parts of the image. Go back to the layers,

deactivate the Normals layer, and add a Curves

adjustment layer while you still have the selection

active. Pull the curve up to the maximum, and you

can see how the object gets brightened just as it was

intended. The image looks overexposed in some

areas, and also some regions might be better off

without the Curves adjustment. Therefore, group the

Curves adjustment layer and add a layer mask to the

group. Invert the mask and paint with the brush only

where you want the adjustment to affect the image.

11

OBTAIN THE DESIRED MASK

The image needs more light coming from

above, and instead of going back to the 3D scene,

making tests, rendering again and losing several

hours, you can use this technique, and have an

undestructive and controllable tool at your disposal.

In order to obtain the desired mask, play with the

Hue/Saturation options – the values that work best

are +30 for Hue, +100 for Saturation and -30 for

Lightness. You can see how the surfaces that face up

are all covered in white, while the rest of the image is

black, which means we can use this result to

illuminate from above.

13

REPEAT THE PROCESS

You can always reactivate the Normals

layer and tweak the Hue/Saturation settings until

you get other useful masks. You can direct your

curves to affect surfaces from every side you wish,

and you can also darken areas, not only brighten

them. Always group your adjustment layer, and add

a layer mask to the group to paint over it, so that you

can have maximum control over your work.

10

CREATE MASKS WITH THE NORMALS PASS

The Channel Mixer already offers a

greyscale mask, but in order to have full control of

this technique, you have to use the Hue/Saturation

adjustment layer. As you move the Hue slider, the

image changes, just like if there is a light source that

moves around the object. Also, both the Saturation

and the Lightness sliders can be used in order to

play with the contrast of the mask. This technique is

extremely efficient, because you can rapidly create

masks to act from whichever direction upon the

rendered object.

09

USE THE NORMALS PASS

This render element is a 2D representation of the 3D objects, based on the normal angle of

the camera. The image is made up of tones of red, blue and green, which represent the axes of the

tri-dimensional space (x,y and z). Although often ignored, it can be used to easily create masks, being

based on RGB values,

EASILY CREATE ILLUMINATION MASKS

BRIGHTEN AND DARKEN PARTS OF YOUR IMAGE BY USING THE NORMALS PASS

001 PLACE THE

NORMALS PASSPlace it as the top layer in the 3D group.

We will make masks with it, so it is betterto sit at the top so it is easy to access

throughout the rest of the process

002 ADD

ADJUSTMENT LAYERSLink a Hue/Saturation adjustment

layer to the Normals pass, and also add and link a Channel Mixer

adjustment layer above it

003 ADJUST THE

CHANNEL MIXERSet the Channel Mixer on

Monochromatic and reduce the Redvalue to the minimum, and then raise

the Green value to the maximum

001

Always group your

adjustment layer, and

add a layer mask to the group

to paint over it, so that you

can have maximum control

over your work

002

003

TECHNIQUES 3D & PHOTOSHOP: THE COMPLETE GUIDE