3 Tips for Better Machine Vision Lighting

August 30, 2019

This is Part 2 of a series on lighting best practices for Machine Vision. The previous entry is available here.

Lighting is one of the most impactful yet customizable elements of machine vision. We’ve seen numerous customers succeed with our lighting solutions, and we’ve gathered some best practices to show how they can work for your product.

1. Minimize glare with side lighting

While unusual shapes, angles, and sizes require careful planning to properly accommodate, reflective products tend to be one of the most common lighting challenges. It just so happens that many industrial use cases feature products with highly reflective materials - glass, metals, plastics, and various coatings. Reflective surfaces will create glare from both direct and ambient light sources. Fortunately, there are ways to ensure the camera sees a clear image.

Most reflective products can be effectively handled using 1-2 side lights. These lights should be placed above and to the side of the product, with diffusers being applied where possible (Note: all Samsara lighting accessories come with built-in diffusers, though additional diffusers can certainly be utilized). If using a single side light, a reflector facing the light source will even out lighting across the product.

In the examples above, we show how an eyeshadow kit with a reflective plastic cover is captured in various lighting setups. Direct lighting creates glare that can interfere with inspection capabilities, while side lighting produces a clear image for inspection.

2. Use backlighting for transparent or translucent objects

Transparent glass and plastic products pose the unique challenge of background considerations. Because transparent objects allows light through, the background can influence both lighting of the product as well as readability of inspection elements. A reflective background could create glare, and a cluttered background could make text more difficult to read.

For the best results, we recommend utilizing backlighting to handle transparent products. A large area light placed in the background can hide small imperfections in the object while also illuminating inspection features. This works for use cases involving clear liquids as well, allowing fill level inspections to be easily performed.

In the examples above, we show how a transparent package of catheters is captured in various lighting setups. Direct lighting results in heavy glare that interferes with inspection performance, while backlighting allows for the catheters to be clearly and evenly illuminated.

3. Optimize digital settings

While physical lighting is a great way to highlight your products, digital settings can also enhance your inspections. From camera setting adjustments such as Exposure and Focus to post-processing filters that improve sharpness and lighting uniformity, the Samsara user dashboard allows you to perform image adjustments with real-time feedback. We will provide detailed, setting-by-setting explanations in the next lighting series blog post.

These filter options are especially useful in situations involving limited flexibility in customizing external lighting or significant, unavoidable ambient lighting that impacts inspection quality. The recommended adjustments will vary significantly by situation, but the general rule of thumb is to highlight features of interest whenever possible.

In the examples above, we show how a product affected by ambient lighting can be captured using various camera settings and image filters.

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