Not even that. Apple recieves a visual derivative of the image, such as a low-resolution version, for manual review. The downside it that this makes the human

Not even that. Apple recieves a visual derivative of the image, such as a low-resolution version, for manual review. The downside it that this makes the human review process tricky. Because there is, understandably, no actual CSAM image to compare the visual derivative with. Images that look similar enough (contain nudity or a child in a swimsuit) may get past the human review process.