Basic post-production in Photoshop
Introduction
This page covers basic techniques in Photoshop to improve or change a render when needed.
Composition and cropping
When a render is finished, some adjustments can still be made to the overall composition of the image and put more focus on a specific region in the image. With the cropping tool there are several options available while you exclude parts of the render: adjusting rotation and adjusting perspective.
Once a frame is drawn, some new options will be visible. There are two options available for the cropped area.
- Delete
- Hide
Hiding the cropped area is preferable in most cases as the cropped area can be restored at any time.
After hiding the cropped area, the image can still be moved around within the visible area. To reveal the cropped area, use the ‘Reveal all’ command found in the Image menu.
Adjusting rotation
To rotate, simply place your cursor anywhere outside the frame. The cursor will indicate that the frame can be rotated.
Adjusting perspective
To adjust the perspective of an image while you are cropping, check the perspective box in the cropping options toolbar. Note that that the perspective option won´t be available if the cropped area is set to hide. While the perspective box is checked, each corner of the frame can be dragged. A modified frame will be formed back into a rectangle, forcing the perspective out of an image and straightening the image. In this process the image might end up with a wrong scaling. This usually occurs if the image was in strong perspective to begin with.
Adjustment layers
Adjustment layers are useful for a project as none of the adjustments are permanent. The adjustments are stored in a different layer rather than being applied directly on the original image/render. They can be turned off or tweaked at any moment in the process. The adjustment layers can be found in the layers tab or under the layers menu.
There are two ways an adjustment layer can work.
- An adjustment layer will have an effect on all the layers below it.
- An adjustment layer will have an effect only on the layer below it.
This type of control will help you sort the adjustment layers and other layers and not have unwanted effects on certain layers. When an adjustment layer is created, it will have an effect on all the layers below it by default.
To change an adjustment layer into working on the layer directly below it, use the ‘clip to layer’ button found at the bottom of every adjustment layer panel. A little arrow will appear next to the adjustment layer, indicating it is working only on the layer directly below it.
Editing the render
Adjusting Exposure
The Exposure adjustment layer can help you correct the light setting in your render, which can be hard to set in the rendering software itself. With the Exposure adjustment layer you can increase or decrease the exposure. With the added mask you can exclude where the Exposure adjustment layer has an effect. By doing so, you can emphasize parts of the render and create the desired effect. To exclude parts of the adjustment layer, apply either gray or black. The darker the grey color the more you will hide of the adjustment itself. A better method than using grey is using black, but lowering the opacity. With translucent black you are able to stack the black each time it is applied, going from transparent to opaque.
Levels
The Levels adjustment layer can be used for correcting the color values of an image, to force mid-tones into shadows or highlights. For example, an image can look washed out. The Levels adjustment layer can tell you the range of colors your image consists of.
If a render is not lacking in the level of shadows or highlights, the Levels adjustment layers can then be used for creating extra contrast or general tweaking. The histogram analyses the picture and shows the range of the colors i.e the ‘levels’.
The following example shows most of the colors in the image consist of shadows and mid-tones, decreasing in amount for the highlights with a thin spike at the end. This large spike resembles the pure whites in the image, the brightest color possible.
The next example shows that the histogram has shifted, it doesn´t reach the far most left anymore. By moving the black point the edge of the histogram, this point becomes the far most left. Meaning the colors are pushed toward shadows.
Color corrections
Curves
One of the most versatile tools for color corrections is the Curves adjustment layers. The Curves adjustment layer works with a single line that represents the ratio between the input and output colors of an image. This line can be manipulated to change the ratios between the input and output. Moving the line up will add color intensity and moving the line down will subtract color intensity. This can also be done for red, green or blue channel individually.
Adding or subtracting in the RGB channel will result in an increase or decrease of intensity. Adding or subtracting in a red, green or blue channel individually will have to following results.
Fixing small errors
Clone stamp tool
The Clone stamp tool is a brush with copy and pasting feature with the qualities of a normal brush. With the Clone stamp tool you can make small to big adjustment to your image, correcting mistakes or hiding parts of an image.
The Clone stamp tool works with selecting a source first. After a source has been selected, you brush will preview the source before it is applied. This source and result will be locked and move parallel with each other after brushing the first time.
When using the Clone stamp tool it is advised to do this in a non-destructive manner. To do so, create a new empty layer and set the sample mode to ‘Current & Below’. This will allow the Clone stamp tool to work in the empty layer while using the layer below as a source. All the changes will be drawn on the empty layer and won’t affect the original image.
For example, the white chair is not desired. With the careful selection of the right sources the chair is able to be removed. In the process switching sources might be necessary multiple times. If the re-worked area looks messy, the Blur tool can help soften the messy area.
In some cases, the link between the source and the result might need adjusting. Such as the scale between the two, the rotation between the two or simply mirroring the result from the source. These additional option can be found under:
This tab will provide the needed tweaking possibilities:
- Slots for saving different sources.
- Adjusting the offset between source and result.
- Mirroring the result for Width and/or Height. Note: For Photoshop versions before CS5, mirroring is done by entering a negative scaling number using the minus sign.
- Scaling number for Width and Height.
- Rotating the result, in degrees.
Vignetting
Vignetting can be achieved in many ways, using solid layers or adjustment layers. Using a solid fill layer is a good choice. By tweaking the mask for this solid fill layer it is possible to create the preferred shape and softness.
To create a new Solid fill layer, choose:
A small window will appear, after clicking ok you can choose a color. For this example, black will be used. Using the Elliptical marque tool a selection can be drawn from one corner to the diagonal opposite corner. While the mask is selected, the elliptical area can be painter black.
To create the soft edges, the mask can be edited. To do so, right click the mask of the Exposure adjustment layer, choose ‘Refine mask’. Increasing the Feather value will soften the hard edge that was created earlier. Using a different opacity for the fill layer will help you tweak the vignette further. Double clicking on the little square color indicator of the Solid fill layer will let you change the color of the vignette at any time.
Placing a person
Placing people can have different effects on an image, like a sense of scale. It is best to have a person on a clear solid background. So the background can be removed from the person. To select the solid color around a person, choose:
Color range will allow you to select the color around the person, which will result in a complete selection of that color. After the selection is complete, you can delete the surrounding. Saving the image as a .PNG file will keep the transparent surrounding intact and the image will be ready to be imported in any project.
Once a person is placed in a scene, it might need some adjusting to fit in its surroundings. In this example, the person doesn’t have the correct lighting and needs slight perspective correction.
The Perspective tool can be found under:
Using the top middle handle, you can move the person in line with the lines of the image.
With an adjustment layer like Curves, Levels or Exposure you can correct the brightness or darkness of the person to fit into the light setting of the image. Using a basic white brush you can indicate that the person is being lit from the top, like the scene indicates.
Adding a shadow
To prevent the person from floating, a shadow is needed. Since the light is almost directly from the top. This person will have a very short shadow. In such a case a black brush could suffice, in most cases a duplicate of the person itself needs to be turned into a shadow.
First, create a duplicate of the person, then right click on the duplicated layer´s icon and click on ´Select Pixels´. This will create a selection at the outlines of the person. After that click:
Choose black as the fill color.
Flip the duplicate vertically, choose:
Using the other Transformation tools, you can get the shadow in the correct position. Skew in particular is very useful for this task.
Step by step
Depending on what needs to be presented, a rendered image could have little tweaks or major adjustments. In the following example a render will adjusted to a point it can be considered unrealistic, but artistic.
Starting with a basic background where the color has shifted towards blue with a Curves adjustment layer
The background is placed behid the render.
A person is added.
Two Curves adjustment layers are used. One to shift the center towards blue and one to shift the remaining parts towards red. Two Exposure adjustment layers are added. One to add exposure to the center of the image and one to decrease the exposure on the outer parts.
Some dust is added with Photoshop.
Some wild growth is added.
For the ivy two Exposure adjustment layers are used. One to add exposure to the leaves facing the light and one to decrease the exposure on the leaves that are behind the column.
Added sky light with Photoshop.
Vignetting for the final image.
