Repairing Artifacts and Cosmetic Defects

Various cosmetic repair tools are available to correct blemishes and other artifacts in images. Choose from the commands below to address various types of defects. The appropriate method depends on the defect's nature, whether it occurs at fixed or arbitrary locations in different images, and whether the defects are isolated or in groups. Additionally, scripts may be developed to apply custom repair strategies.

Choosing a Repair Method based on the Defect Type

The table below matches the defect type and location to a command for correcting it.

Defect Type	Location	Commands
High or Low pixels, single or pairs	Fixed	Create Pixel Mask Apply Pixel Mask

High or low pixels, single or pairs	Arbitrary	Interactive Repair Combine Image Set Clean Image Set Cosmic Ray Filter Median Filter

High or low pixels, after subtracting the dark current	Any	Create Pixel Mask Apply Pixel Mask Interactive Repair Clean Image Set

CCD hot columns and cold traps	Fixed	Edit Blemish Mask Apply Blemish Mask

Clusters larger than 1 or 2 pixels	Fixed	Edit Blemish Mask Apply Blemish Mask

Cosmic rays and ionizing radiation	Arbitrary	Combine Image Set Clean Image Set Cosmic Ray Filter Median Filter

Stars	Arbitrary	Star Removal

Cosmetic Repair Commands

Apply Blemish Mask	Repairs lines and rectangular regions that are always located at the same locations, including hot columns, cold traps, and blemishes larger than 1 pixel in area.
Apply Pixel Mask	Repairs isolated pixels using coordinates loaded from a file containing x,y positions of the bad pixels. Use this for repairing pixels that always are located at the same locations, such as hot or cold pixels.
Combine Image Set	Defects that do not repeat among image set members are removed by combining with a rejection or median method and normalization. For details, see Combine Image Set and Image Combining Strategies.
Clean Image Set	Detects and repairs transient defects that vary in location, such as cosmic ray and ionizing radiation events.
Cosmic Ray Filter	Automatically detects and repairs isolated pixels and small clusters of hot pixels caused by cosmic rays and ionizing radiation.
Create Pixel Mask	Used to create a pixel mask by detecting isolated pixels that have very high or low values.
Edit Blemish Mask	Creates and edits a blemish mask (a text-based description of blemish locations).
Edit Pixel Mask	Edits an existing pixel mask or creates new a pixel mask by entering coordinates into a grid.
Interactive Repair	Used to interactively identify and repair pixels using mouse clicks and a marking cursor.
Star Removal	Used to remove stars from the image. This is typically used before doing photometry on the image.

Choosing a Repair Method based on the Defect Type

Cosmetic Repair Commands

Related Topics