Vis Flag Map Product

Metadata

Data product name

DpdVisFlagMap

Data product custodian

VIS

Name of the Schema file

euc-vis-FlagMap.xsd

Processing Element(s) creating/using the data product

Flag Map

Processing function using the data product

VIS

Proposed for inclusion in EAS/SAS

Yes

Detailed description of the data product

Flag maps are useful for selecting suitable objects in the image and removing invalid pixels. They are 32 bit integer values. These integers are not unsigned.

The table and flags description below are representative of the latest version of the flags definition.

The Flagmap data format is defined in the data model and in the wiki page VIS_Flags.pdf.

Changes introduced by the PF version

PF 14.0

  • Pixel flag NEARCHARINJ (bit 16) suppressed, as it was never used.

  • New pixel flag QUADEDGE (bit 6): pixel near a quadrant edge.

  • New pixel flag CR_REGION (bit 9) for pixels in a region containing too many cosmic rays. This flag is included in INVALID flags.

  • New flags BAD_COLUMN (bit 7) and BAD_CLUSTER (bit 8) for bad pixels.

  • Flag TX-ERROR renamed NO_DATA.

PF 15.0

  • CR_REGION is no more included in flag INVALID.

  • OVRCOL added to INVALID.

  • Deletion of flags that have never been used:

EXTOBJ (bit 13): extended object: pixel part of an extended astronomical object
SCATLIGHT (bit 14): scattered light: pixel affected by non diffuse scattered light
SATURATEDSTAR (bit 19): saturated star: pixel affected by a saturated star PSF
CTICORRECTION (bit 20): charge transfer inefficiency correction: pixel affected by CTI correction by more than 1 (TBD) ADU
PF 17.0

  • No changes

PF 18.0

  • Flag ‘GOOD’ (flag value 0) removed from the list of flag names. Flag values remain unchanged.

PF 18.1

  • Add flag ‘STACK_CR’ (bit 11) for internal purpose.

PF 18.4

  • Add flag ‘LOWVAR_COL’ (bit 10) for internal purpose.

PF 18.5

  • Add flag ‘COSMIC_LA’ (bit 25) and ‘COSMIC_DEEP’ (bit 26).

  • Rename ‘STACK_CR’ (bit 11) to ‘COSMIC_STK’ (bit 27).

Table

Bit

Bit Mask

Flag Value

Flag Name

0

0x00000001

1

INVALID

1

0x00000002

2

HOT

2

0x00000004

4

COLD

3

0x00000008

8

SAT

4

0x00000010

16

COSMIC

5

0x00000020

32

GHOST

6

0x00000040

64

QUADEDGE

7

0x00000080

128

BAD_COLUMN

8

0x00000100

256

BAD_CLUSTER

9

0x00000200

512

CR_REGION

10

0x00000400

1,024

LOWVAR_COL

12

0x00001000

4,096

OVRCOL

15

0x00008000

32,768

CHARINJ

17

0x00020000

131,072

SATXTALKGHOST

18

0x00040000

262,144

STARSIGNAL

21

0x00200000

2,097,152

ADCMAX

22

0x00400000

4,194,304

NO_DATA

23

0x00800000

8,388,608

STITCHBLOCK

24

0x01000000

16,777,216

OBJECTS

25

0x02000000

33,554,432

COSMIC_LA

26

0x04000000

67,108,864

COSMIC_DEEP

27

0x08000000

134,217,728

COSMIC_STK

Flags description

Bit 0 - INVALID

Automatic interface flag identifying pixels with an arbitrary value which shall not be used for anything. Combination of HOT, COLD, SAT, COSMIC, GHOST, BAD_COLUMN, BAD_CLUSTER, OVRCOL, CHARINJ, SATXTALKGHOST, ADCMAX, NO_DATA.

Bit 1 - HOT

Hot pixel: defective always bright pixel.

Bit 2 - COLD

Cold pixel: defective unresponsive pixel.

Bit 3 - SAT

Saturated pixel: pixel near or above blooming threshold.

Bit 4 - COSMIC

Cosmic ray: pixel affected by a cosmic ray.

Bit 5 - GHOST

Optical ghost: pixel affected by an optical ghost.

Bit 6 - QUADEDGE

Quadrant edge: pixel near a quadrant edge, which causes pixel-size and nonlinear response variations.

Bit 7 - BAD_COLUMN

Part of a column of bad pixels which have an abnormal behaviour, e.g. hot, cold, low noise, high noise.

Bit 8 - BAD_CLUSTER

Secondary bad pixel which is part of a cluster of immediate neighbours of hot or cold pixels.

Bit 9 - CR_REGION

Pixel belonging to a region in which detected cosmic rays per pixel ratio is too high for correct processing.

Bit 10 - LOWVAR_COL

Pixel belonging to a column with an abnormally low variance.

Bit 12 - OVRCOL

Overflow column: pixel affected by a neighbouring saturated pixel.

Bit 15 - CHARINJ

Charge injection: pixel part of charge injection line, not exposed.

Bit 17 - SATXTALKGHOST

Saturated crosstalk ghost: pixel affected by electronic crosstalk caused by a saturated pixel.

Bit 18 - STARSIGNAL

Star signal: pixel affected by a star psf.

Bit 21 - ADCMAX

Analog-to-digital-converter maximum: pixel at maximum adc value (65,535) before vis processing.

Bit 22 - NO_DATA

No data available for this pixel (being 0 adu in vis input raw frame), due to transmission error, truncated/incomplete raw file, failing quadrant, ccd or roe, or anything else.

Bit 23 - STITCHBLOCK

Photolithographic stitch-block boundary: pixel may have a non-nominal size.

Bit 24 - OBJECTS

Detected objects in science image, currently non-zero pixels in objects sextractor check-image.

Bit 25 - COSMIC_LA

Pixel affected by a cosmic ray, as detected by the lacosmicx algorithm.

Bit 26 - COSMIC_DEEP

Pixel affected by a cosmic ray, as detected by the deepcr algorithm.

Bit 27 - COSMIC_STK

Pixel affected by a cosmic ray detected using the stack.