Dec 21, 2020
Catchoom Team
In order to make your items (objects) recognizable, you need to represent them using reference images. You can use one or several reference images to represent an item. Good reference images are crucial to boosting the image recognition performance and keeping your users happy.
The view of an Image Recognition item in the CraftAR Service (see screenshot below) shows an Image Quality field with an orientative 5-stars rating indicating how well that specific image is expected to work in normal conditions when used as a reference image for IR.
Note that the Image Quality rating we provide does not take the repetitiveness of the pattern into account, which may also negatively affect the recognition performance.
Hence, the rating feature mainly serves to identify reference images that will surely not work well. So it is always wise to eventually test the recognition on the actual image or object, too, to make sure that the experience works the way it is expected.
Our Image Recognition technology relies on the texture (visual elements) in the images to recognize them despite having different viewpoints, changes in illumination, occlusion, etc. This is why the highest quality scores are given to images that show rich texture.
The remaining of this article will help you to learn how to prepare reference images for your use cases. Note that most of the tips described below are specific to reference images, and you do not need to apply them to query images (read the separate article about those).
This article is divided into the following sections:
Important: All objects with a certain texture or markings work well with our technology, e.g.:
In general, the more uniquely textured the object’s surface the more reliable and resilient it is to reflections, occlusions, tilting, and blurring during recognition.
Figure 1. Examples of perfect reference images for objects that work well with our technology:
Although we are working hard on improving our technology, certain types of objects do not work well with our solution.
Important: Objects that do not work well include objects that are pattern-less (e.g. with only solid color), are dynamic in nature (e.g. animals), or have thin bodies (e.g. cables, pencils, etc.).
Figure 2. Examples of reference images depicting objects that do not work well:
Note that some above examples (e.g.: (h)) would obtain high Image Quality scores because they have strong visual patterns well distributed all over the image.
Important: A good reference image should only show the object that you want to represent. Every item (object) should be represented by at least one image depicting its frontal face.
Other important things to remember are:
The example below shows how to prepare the best reference image for recognizing this robot design on a business card.
Figure 3. Selecting perfect reference image for recognizing this robot design on a business card:
Important: In most cases, one reference image is enough. Even in cases of non-planar objects, such as cans or bottles, using one reference image showing their most representative frontal face gives good results.
However, there are some special cases where additional images are helpful: