Chromakeying a Digital Still Camera Image with Stop MotionMaker Advance V1.8.

 Note: The system will reduce larger imported images to a  maximum size of 2000 x1100 for use within the application (to limit memory use).  A larger size capable version can be produced on request.

Background Information

To give the user a better understanding of the process, some background on each control is given before the chromakey tutorial.

Initial Range Normally the first slider to be adjusted, works from either finding prominent green or blue (depending on setting) pixels from the background plate and replacing them with pixels from the chromakey image.   It starts from light colours and works to dark.   The higher the setting the darker the colour that will be chromakeyed.

1 to 8 Range This slider controls the loaded  chromakey colours (from the main image)   1 to 8.  This adjustment controls how far either side of the loaded colour will be replaced by chromakey pixels.

9 to 15 Range The second slider controls the loaded  chromakey colours (from the main image)   9 to 15.   This adjustment controls how far either side of the loaded colour will be replaced by chromakey pixels.

Spill Range This slider adjust how far either side of the selected spill colour will be effected by the ‘Spill Adjust Colour’ control.  Once again this will only work 7 pixels in from the chromakey edge

Spill Adjust Colour This slider adjust how much the green or blue component of the select colour will be reduced by.      Note: If it is reduced too far, the select green colour will turn to red.

Transparency This slider controls how much grey background image is mixed with the main image.   This function used with a smooth glass cup and a bright/strong colour image, can give the illusion of chromakeying through glass.

Blur Chroma Image This slider is used to blur the chromakey background image to change the ‘depth of field’ or to match a high resolution image to a video image.  It will only effect the background chromakey image.

Add Chroma Mat When selected, this function will force the pixels draw upon in the main image to have the chromakey image on.  This is also used to paint over support wires etc.

Subtract Chroma Mat When selected, this function will force the pixels drawn upon in the main image to have the chromkey off.  Use to stop problem colour parts of the figure from being ‘eaten’ or replace by the chromakey image when it is not wanted.

Reset Chroma Mat When selected, this function will reset the pixels drawn upon back to a normal state (not forced on or off).

Shrink to fit via Sliders When selected, the chromakey image will reduce in size to match the position of the x/y sliders.

Lock mat When chromakeying live, will lock the set chromakey mat to reduce video noise when using a video chromakey background and the figure is not moving.

Feather Inner Edge Selects how deep a blur effect will be used on the chromakey inner edge. Used to smooth up the digitally produced chroma edge.

Feather Outer Edge Selects how far out a blur effect will be used on the chromakey outer edge.  Used to smooth up the digitally produced chroma edge.

By using a digtial still camera (DSC), broadcast quality chromakey images can be produced with excellent chromakeys and greatly reduced (if not totally removed) chromaKey colour spill from the puppets/figures edges.  The following tutorial takes you through producing a chromakey image with Stop MotionMaker Advance V1.8 and a Digital Still Camera (in this instance a Canon 2SIS). A USB Webcam (Logitec 4000) is also being used in the tutorial as a separate video assist.  

First connect your camera to the computer and open Stop MotionMaker Advance. Then select ‘New ‘ and then take a frame for system use.

Now open the Chromakey (Background) Viewer by Selecting B/Chromakey

Select either the ‘Green Screen’ or ‘Blue Screen’ check box to suit what is being used.

Adjust the ‘Colour Range’ slider until there is no Green or Blue pixels, but not to the point were it affects the figure.

Open a jpg, video, bmp or live capture image by selecting the relevant button (in this case ‘Open Jpeg’.

This image is now chromakeyed with the figure. Select ‘Chromakey Controls.

Remove the spill colour by selecting (in this case) button No 9 and left clicking over the spill pixel. Adjust the ‘Selected range’ second slider for effect, but not to the point of ‘eating’ into the figure. Load more colours in the same way and adjust to suit. Note that the Selected Range first slider controls chroma colours 1 to 8 while the second slider controls chroma colours 9 to 15.

Note: The ‘feather Edge’ controls have set themselves to zero to ensure unmodified pixels are loaded.

To revert to the previous settings select ‘Reset’ or in this case set feather outer Edge to ‘0’ and Feather inner Edge to ‘1’.

Chroma colour Spill has now been removed.  Next, we will remove the support wire.

Select the ‘Add Chroma Mat’ check box.

Draw with the mouse (left click and drag) this will open the chromakey layer and expose the image.

The processing is completed when the mouse button is released.

The Pen size can be adjusted from 1 to 50 pixels.

Final image is now completed which can be saved by selecting ‘Save Changes’.

Carry on importing frames and processing/saving each image.

To make a AVI movie out of your images, just select the ‘Bmp to AVI’ button in the main window.

The image below is a screen capture of Stop MotionMaker Advance with a larger 2592 x 1944 image after it has been processed (support wire still to be removed).   The ‘zoom’ window shows were colour spill has been reduced.

It must be noted that when working on images of this size, it  will take a few seconds to re-process each image when adjustments are made.