yarpdatadumper with png files

[triccyx]

Describe the bug
Using yarpdatadumper can not save images in png format. While bmp format works (--image)

To Reproduce

yarpserver --write
yarpdev --device grabberDual --subdevice usbCamera --camModel ultrapython --d /dev/media0 --name /grabber
yarpdatadumper --name /log --rxTime --txTime --type image_png --connect /grabber

Expected behavior
Inside folder log I can find the dumped images. No images found.

Screenshots
na

Configuration (please complete the following information):

• OS:Ubuntu 20.04
• yarp version:YARP version 3.4.101+20210309.4+gitae65e3050+dirty
• compiler:gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0

Additional context
Errors issued repeatedly:

libpng warning: Invalid bit depth in IHDR
libpng error: Invalid IHDR data
[ERROR]/home/triccyx/Documents/robotology-superbuild/robotology/YARP/src/libYARP_sig/src/yarp/sig/ImageFile.cpp:316 bool SavePNG(char*, const char*, size_t, size_t, size_t, png_byte, png_byte): [write_png_file] Error during writing header
libpng warning: Invalid bit depth in IHDR
libpng error: Invalid IHDR data
[ERROR]/home/triccyx/Documents/robotology-superbuild/robotology/YARP/src/libYARP_sig/src/yarp/sig/ImageFile.cpp:316 bool SavePNG(char*, const char*, size_t, size_t, size_t, png_byte, png_byte): [write_png_file] Error during writing header

Important notes:

• Try with the new UltraPython camera
• yarpdev on ARM arch, yarpdatadumper on X86 or Arm has the same result

[pattacini]

By launching:

$ yarpdev --device fakeFrameGrabber &
$ yarpdatadumper --connect /grabber --type image_png

I managed to get the PNG images stored correctly.

Could you do the same test on your system @triccyx.

[triccyx]

I have tried on the ARM Enclustra board and all seems ok. The files are generated. No errors detected.

[pattacini]

yarpdatadumper calls the library services SavePNG() developed by @randaz81.
Maybe he can provide some insights.

[triccyx]

I have tried with jpg with success.

yarpdatadumper --name /log --rxTime --txTime --type image_jpg --connect /grabber

[randaz81]

@triccyx I suspect that the error you see is due to the fact that your image is not a standard rgb image and libpng does not know how to handle it. Could you provide more details on the image format or give me access to your camera for a check? Anyway, looks like this discussion will become a standard yarp issue (bug/feature request).

PS: the difference between png and jpg is the following: png is lossless.

[pattacini]

Anyway, looks like this discussion will become a standard yarp issue (bug/feature request).

Indeed it was and then was converted into a discussion – I don't know why.

[triccyx]

@triccyx I suspect that the error you see is due to the fact that your image is not a standard rgb image and libpng does not know how to handle it. Could you provide more details on the image format or give me access to your camera for a check? Anyway, looks like this discussion will become a standard yarp issue (bug/feature request).

PS: the difference between png and jpg is the following: png is lossless.

Yes, you are welcome when you can.