Image Stacks (Photoshop Extended); About Image Stacks; Creating An Image Stack - Adobe Photoshop CS6 User Manual

Image Stacks (Photoshop Extended)

About image stacks

Creating an image stack

Use a script to create an image stack
About image stacks
An image stack combines a group of images with a similar frame of reference, but differences of quality or content across the set. Once combined
in a stack, you can process the multiple images to produce a composite view that eliminates unwanted content or noise.
You can use image stacks to enhance images in number of ways:
To reduce image noise and distortion in forensic, medical, or astrophotographic images.
To remove unwanted or accidental objects from a series of stationary photos or a series of video frames. For example, you want to remove a
figure walking through an image, or remove a car passing in front of the main subject matter.
Image stacks are stored as Smart Objects. The processing options you can apply to the stack are called stack modes. Applying a stack mode to
an image stack is a non-destructive edit. You can change stack modes to produce different effects; the original image information in the stack
remains unchanged. To preserve changes after you apply the stack mode, save the result as a new image, or rasterize the Smart Object. You can
create an image stack manually or using a script.
Creating an image stack
For best results, images contained in an image stack should have the same dimensions and mostly similar content, such as a set of still images
taken from a fixed viewpoint, or a series of frames from a stationary video camera. The content of your images should be similar enough to allow
you to register or align them to other images in the set.
1. Combine the separate images into one multi-layered image. See Duplicate layers.
Note: An image stack must contain at least two layers.
You can also combine images using a script (File > Scripts > Load Files into Stack).
2. Choose Select > All Layers.
Note: To make the Background layer selectable with the All Layers command, you must first convert it to a regular layer.
3. Choose Edit > Auto-Align Layers and select Auto as the alignment option. If Auto does not create good registration of your layers, try the
Reposition option.
4. Choose Layer > Smart Objects > Convert to Smart Object.
5. Choose Layer > Smart Objects > Stack Mode and select a stack mode from the submenu.
For noise reduction, use the Mean or Median plug-ins.
For removing objects from the image, use the Median plug-in.
The output is a composite image the same size as the original image stack. You may need to experiment with different plug-ins to get
the best enhancement for a particular image.
To change the rendering effect, choose a different Stack Mode from the submenu. Stack rendering is not cumulative—each render effect
operates on the original image data in the stack and replaces previous effects.
Stack modes
Stack modes operate on a per-channel basis only, and only on non-transparent pixels. For example, the Maximum mode returns the maximum
red, green, and blue channel values for a pixel cross section and merges them into one composite pixel value in the rendered image.
Rendering plug-in name
Entropy
Result
entropy = - sum( (probability of value) *
log2( probability of value) )
Probability of value = (number of
occurrences of value) / (total number of
non-transparent pixels)
Comments
The binary entropy (or zero order entropy)
defines a lower bound on how many bits
would be necessary to losslessly encode
the information in a set.
To the top
To the top