It has this note at the bottom: "Note that I chose an unusually long chart to exemplify an extreme case of aspect ratio stretching. Still, 512px² is enough. T

It has this note at the bottom: "Note that I chose an unusually long chart to exemplify an extreme case of aspect ratio stretching. Still, 512px² is enough. This is two_col_40643 from ChartQA validation set. Original resolution: 800x1556." But yeah, ultimately which resolution you need depends on the image content, and if you need to squeeze out every bit of accuracy, processing at the original resolution is unavoidable.