i think i found a small bug in line 288 of file : components/com_cobalt/fields/image/image.php
i changed this line
$full_file_path = JPATH_ROOT . DIRECTORY_SEPARATOR . $this->value['image'];
to
$full_file_path = JPATH_ROOT . DIRECTORY_SEPARATOR . $file;
this solve deleting picture problem, also i think it's logic, cuz deleteImage() function called from ajax ($this->value['image'] will be empty)
i think i found a small bug in line 288 of file : components/com_cobalt/fields/image/image.php
i changed this line
$full_file_path = JPATH_ROOT . DIRECTORY_SEPARATOR . $this->value['image'];
to
$full_file_path = JPATH_ROOT . DIRECTORY_SEPARATOR . $file;
this solve deleting picture problem, also i think it's logic, cuz deleteImage() function called from ajax ($this->value['image'] will be empty)