How to convert CompressedImage to Image?

asked 2017-02-18 10:37:17 -0500

baozhang
39 ●11 ●12 ●14

I would like to convert CompressedImage to Image.

rosrun image_transport republish raw in:=/image_raw  compressed out:=/image_raw_converted

Then, I could got image_raw_converted which is CompressedImage and 1/10 data size. I would like to use image_raw_converted as Image. So,

rosrun image_transport republish compressed in:=/image_raw_converted raw out:=/image_raw_converted2

However, the data size increases by 10 times.

Is there any way to convert CompressedImage to Image and also decrease the data size?

answered 2017-02-20 03:10:13 -0500

tushar
26 ●2 ●3 ●6

No. Compression is the way to reduce the size of the data footprint while recording data. This is the principle that governs video data as well, known as codec. The actual data of a recorded movie is lot larger than the one you stream or watch on your computer.

I believe that ros does a pretty good job of compressing incoming image data and hence you see a bloat in the image size when you decompress it frame by frame. You can read the source code of compressions here

If you want to compress it further I would recommend use ros to generate all the images and then compress everything using a video codec using ffmpeg. There is information about that on this stack overflow question.