When in doubt, we advise to use our Android & iOS SDK (https://github.com/nyris/) for best & fastest results.
Submitting the images to nyris’ find API in the right quality is essential to obtaining high precision search results. There are four main image attributes to take care of in order to receive best results from our engine.
- Image Dimensions
- Image Size & File Format
- Image Rotation
Using the right image segment (Object Detection)
We do undertake measures to correct for low source image quality, but those are only a fallback as they reduce matching speed and do not always work perfectly. So as a general rule please keep in mind:
The better the source image quality, the better and faster are the results.
1) Image Dimensions
- Recommended: 1000px (longest side)
- Minimum: 500px (shortest side)
- Maximum: 1500px (longest side)
Please make sure that the final dimension of the image after all pre-processing steps (like cropping, object selection etc.) is at least 500px (shortest side). For best results from the OCR stage we recommend to send us an image of 1000px (longest side). Everything below those values will have a negative impact on matching performance. Everything above those values does not add significant gains in precision and slows down the matching speed.
Main sources for wrong image size are:
- The image is resized before pre-processing steps like cropping or object selection. All cropping & cutting steps should be applied to the original image and then resized & send to us.
Example:
Wrong: Result is a blurry image = recognition, classification & OCR with high failure probability
Right: Most of the relevant image content is still present in the final image send to the API, Logo Detection, Classification give better results and OCR stage even on smaller text parts still possible.
2) Image Size & file format
The nyris API only accepts JPG file format. To provide fast recognition speed we recommend to compress the image file if required to stay below 100kb transferred image size.
- Recommended JPG compression: 80%
- Recommended max. file size: 100kb
As in step 1., compression should be applied in the final step before transferring the image to the API and not before.
3) Image Rotation
The nyris API uses different image recognition algorithms and neural networks to recognize the content of your images. Some algorithms are rotation invariant, some are not. That’s why it’s important to submit the image in the right rotation to our API for best results.
Main sources for wrong image rotation are:
- The EXIF Information is lost during resizing & compression of the image
- >95% of this issues come from Android devices. As each Android manufacturer handles images in different way, they are send to us rotated left or right or not rotated at all.Same devices often deliver the same image in different orientation when used in a slightly different angle. So there is no way to correct the orientation by just knowing the device.
- so far on iOS Devices the images are handed over in the right orientation to our API
Possible Solution for Android:
SLOW
- (adds roughly 1s overhead – depending on device):
- Get Image from Camera
- Get EXIF
- Crop & Resize & Compress Image
- Rotate Image & Write correct EXIF
- Send Image to nyris API
FAST (better customer experience)
- Don’t use Camera to take the image, take a screenshot of the view
- Crop & Resize & Compress Image - (be aware of final image size - original image is much smaller than from the camera, should still be large enough in most cases)
- Send Image to nyris API
As the screen resolution on most modern Android phones by far exceed image dimension requirement for our API, getting the screenshot is much faster than getting the image from the camera and yields a better & faster customer experience.
