Masking and Rotoscoping > Refining the Mask >

# Troubleshooting the Tracer

Every clip has its own challenges and requires a certain amount of tweaking and fine-tuning to achieve the best results.

Problem | One of the Tracer segments (localized keys) on my matte shows noisy black and white artefacts and nothing else. What's wrong?
Possible Cause | The two pickers are sampling luma and/or chroma values that are too similar.
Solution | Try moving one of the pickers to a differently coloured area, or enlarge or reduce the size of one or both of the pickers to include more varied colour information. If there is simply no area in the clip that differs enough, you will need to use an advanced gradient for that segment.

Problem | One of the Tracer segments (localized keys) on my matte appears to be showing the black/white matte information reversed, or as a negative. What's wrong?
Possible Cause | You may have reversed the position of the two pickers.
Solution | Try exchanging the inside picker for the outside one and vice-versa.

Problem | I can't get a good colour sample from the area outside the mask edge in a certain portion of the image. What can I do?
Possible Cause | There is simply none (or not enough) of the needed colour in the immediate area of that particular picker.
Solution | You can drag the picker somewhere further away from the vertex to get a better colour sample. The picker can be located anywhere on the image in order to facilitate the best possible colour sample. Do not, however, place a picker outside the image.

Problem | I'm getting really nice edge detail on my matte, but I'm also getting black/white holes in my matte. Is there anything I can do?
Possible Cause | This may be caused by the generation of random noise and/or artefacts.
Solution 1 | Try the Clean algorithm by clicking the box labelled Clean. You may want to try several different percentages to find the optimal level of cleaning that doesn't effect your edges (the default percentage is 70%). The Clean algorithm works only with the Tracer and pickers on. If you have advanced gradient segments, they will be unaffected. The Clean command works on all vertices with pickers, whether or not they are selected. The area affected by the Clean command is the same area that the pickers affect (see Applying Softness Using Pickers).
Solution 2 | Use the inner border to isolate the problem areas.
Solution 3 | Add a second garbage mask.

Problem | I'm repositioning and rescaling the pickers and the matte goes from having too much softness (overly transparent) to having too little (overly opaque). What can I do?
Possible Cause | The sampled colour range is either too broad or too narrow.
Solution | Locate the areas that have a tendency to become too softened and the picker that is 'responsible' for this by moving the pickers until the matte results change for the worse. Include a larger portion of these softer areas in a picker box. By sampling a fuller range of chroma/luma in this area, a more uniform, averaged effect is created.