Guidelines to take good photos for optimal results:
Photos should be taken from a distance of at least 30 cm.
Zoom in if needed so the fruits will not be very small on the image.
Take at least 3 photos for every inspection.
Slightly change the position of the phone between the photos.
Rotate\Shuffle the fruits between the photos to measure fruits from the bottom layers if relevant.
Every photo should contain no more than 50 fruits visible on the top layer. If you have more, split them to groups and take several photos.
For example if an inspection contains 90 blueberries. They should be split it to 2 groups and take 3 photo of each group, 6 photos in total.
Well-lit environment having ambient light and not a direct light source on the fruits.
Important for color.
Use dark and solid background. Not shiny and not reflective.
When the background is bright, there is a very high contrast and the fruits are seen dark on the photos. Important for color.
Take the photos from above and not from the side of the fruits.
Few samples :