RoseyCubesat-1 carries two small cameras which take raw images at 480 x 360 pixel resolution. The images are composed of a single byte per pixel with bayer colour filter. These images have recently started being downloaded successfully from the satellite, and several people have already noticed this increased activity: https://twitter.com/EU1SAT/status/1659864466907963392?s=20
The RoseyCubesat-1 team has shared the image packet format, allowing us all to try to decode images. The description, given by @depegasus is as follows:
The satellite sends UI AX.25 packets. Images are transmitted in chunks of 80 pixels with a chunk ID. Packets contain the following data struct:
struct{
uint16_t packetId; //0xA4 0x0C
uint16_t sequenceId; //ignore
uint8_t isPreview; //one indicates 48x36 pixel preview, zero indicates 480x360 full resolution image
uint16_t elementId; //image chunk number. 0-21 for previews, 0-2159 for full
uint8_t pixels[80]; //pixel data
}
Since images are sent in raw format, as opposed to jpeg, even partial images can be seen, and the image can be shown filling-in live as more chunks are received.
Resultant image attached. Conversion to colour requires conversion of the bayer filter data. This can be achieved, for example, using the Python open-cv command:
cv2.cvtColor(im, cv2.COLOR_BayerGR2RGB)
Checking in gpredict when the pass will happen I see that the time is on 29/05/2023 11:29 CEST (not CET), which is 29/05/2023 09:29 UTC. Please correct me if I’m wrong and please use UTC timestamps in the future at it helps a lot to avoid any confusion.
Unfortunately this morning’s predicted download did not occur due to the team working on other objectives during the pass. We will try to keep you updated on future planned downloads. Apologies to anyone waiting for new data to test image decoders.
