Image domain, not time domain. A high-frequency signal in time may rapidly go from very high values to very low values. A high-frequency image in space may rapidly go from very bright to very dark.
You should look up how JPEG uses the Discrete Cosine Transform, because it is unreasonably cool. Nearly all modern lossy compression is based on intense cheating in image frequency domains.
Image domain, not time domain. A high-frequency signal in time may rapidly go from very high values to very low values. A high-frequency image in space may rapidly go from very bright to very dark.
You should look up how JPEG uses the Discrete Cosine Transform, because it is unreasonably cool. Nearly all modern lossy compression is based on intense cheating in image frequency domains.