The bottom is the picture run through fotoforensics.com
The black area doesn't have the same level of variation / detail as the rest. That's why it shows black.
The straight lines you can see in the pure white area are due to this being a "mosaic", because Antarctica is "too big" to photograph all at once. However, the mosaic lines only exist in the pure white area. The rest is not too big to photograph all at once.
It is very common to see an amateur analyst force a result into their desired answer. For example, ELA renders a picture that reflects the compression rate. People often post to Twitter comments like "It's real!" or "It's fake!" when the ELA result really indicates a very low quality image or a consistent compression rate. (With ELA, "white" does not mean modified; white means a higher error level potential that must be compared against similar edges and similar surfaces in the picture.)
For example, a photo may show a white edge around a person's hair that stops at the body. This could mean that the head was spliced onto the body. However, it could also identify selective sharpening, editing of the head, editing around the head, or a high contrast between the hair and the background. The picture may also be scaled or resaved by an Adobe application -- both of which could increase the error potential along high-contrast and high-frequency edges. ELA shows where the compression level varies within the picture, but it does not identify what caused the variation.
Top Comment By shill OP
https://greatawakening.win/p/15IrKrFHHu/x/c/4Ob8dfyhtoo
FotoForensics.com has lots of great info and warns against making this exact mistake. https://fotoforensics.com/tutorial.php?tt=mistakes
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Mistake #2: Forcing an Answer
It is very common to see an amateur analyst force a result into their desired answer. For example, ELA renders a picture that reflects the compression rate. People often post to Twitter comments like "It's real!" or "It's fake!" when the ELA result really indicates a very low quality image or a consistent compression rate. (With ELA, "white" does not mean modified; white means a higher error level potential that must be compared against similar edges and similar surfaces in the picture.)
For example, a photo may show a white edge around a person's hair that stops at the body. This could mean that the head was spliced onto the body. However, it could also identify selective sharpening, editing of the head, editing around the head, or a high contrast between the hair and the background. The picture may also be scaled or resaved by an Adobe application -- both of which could increase the error potential along high-contrast and high-frequency edges. ELA shows where the compression level varies within the picture, but it does not identify what caused the variation.