Thebe draft at 60ppd, manually registered, stacked by darkest of red and green channels, narrow crop, magnified 5-fold, higher dark-level

2025-01-05 15:33 UT
Credit : NASA / JPL / SwRI / MSSS / Gerald Eichstädt © cc by
Submitted By : Maquet-80
Mission Phase : PERIJOVE 68

PJ 68 images #21 and #22 rendered separately as drafts at 60 ppd with the model assumption that all targets are at infinity. Relative linear weights 0.88 for red, and 1.0 for green were used. The intermediate images are stored square-root encoded relative to linear radiometric calibration. Then for each of the two images, the darkest of the red and green channel was calculated. The two derived images were registered manually with an accuracy of about one pixel at 60 ppd, then again combined by calculating the darkest. The darkest of the four exposures is used rather than the mean in order to reduce the heavy image noise caused by energetic particle impacts.

The resulting stacked image was then stretched in a linear way such that the brightest pixel is almost saturated and the assumption that the background level is almost black. The image is cropped around Thebe, and further 5-fold enlarged using the 3rd degree interpolation convention. The assumed dark level is increased in a linear way such that less backgound noise remains visible. But some low-brightess information along Thebe's limb may also have gone lost.

Take the image with a grain of salt since it's enlarged 10-fold with respect to the raw data, and there is a high background noise in the raws.