Libpng warning during feed updates


Collecting feeds via crontab every hour , these warning messages are being sent to me via mail.
Is there anyway to mute these libpng warnings but still receive the crontab mails , just-in-case there is a problem with the feed update process ?

libpng warning: iCCP: profile 'icc': 'RGB ': RGB color space not permitted on grayscale PNG
libpng warning: iCCP: known incorrect sRGB profile

Tiny Tiny RSS v17.12 (c30f5e1)
Debain 9.3 , PHP 5.6.30 , MariaDB 10.1.26



use something like update.php 2>/dev/null

other than that idk


OK , added , Thanks @fox