Rekognition - Invalid ParameterException problem

Question

Greetings,
I've set up a successfully run a python script that will take a source image and do facial comparision against an S3 image sub-directory.  However, when I add a .png which does not have any faces in it, I get this error:

***Error comparing source/isla.JPG and fred/safewatch.png: An error occurred (InvalidParameterException) when calling the CompareFaces operation: Request has invalid parameters***

I do have other .jpg images that don't have faces in them and my code is set to print, 'nope, no match in' image name.  Which does work nicely. Like the isla.JPG above compared to a .jpg image of a tent with no people. It works, no problem.
My question is: When rekognition throws up the error I mention, is there a way to get more detailed information as to why that particular image isn't liked.  Any thoughts gratefully appreciated.

Rick

Accepted Answer

Hi THere

That error usually means no face was detected.

From the [documentation](https://docs.aws.amazon.com/rekognition/latest/APIReference/API_CompareFaces.html): `If no faces are detected in the source or target images, CompareFaces returns an InvalidParameterException error. `

Make sure you are handling errors in your code properly.  Heres an example.  Its using DetectLabels, but the error handling would be similar for CompareFaces

```
import boto3

rekognition = boto3.client('rekognition')

try:
    response = rekognition.detect_labels(Image={'S3Object': {'Bucket': bucket, 'Name': photo}})
    labels = response['Labels']
    
    print(f"Detected labels for {photo}")
    for label in labels:
        print(f"{label['Name']}: {label['Confidence']}")
        
except rekognition.exceptions.AmazonRekognitionException as e:
    print("Could not complete operation")
    print(f"Error Message: {e.message}")
    print(f"HTTP Status: {e.response['Error']['Code']}")
    print(f"AWS Error Code: {e.response['Error']['Code']}")
    print(f"Error Type: {e.response['Error']['Type']}")
    print(f"Request ID: {e.response['ResponseMetadata']['RequestId']}")

except Exception as e:
    print(f"Internal error occurred communicating with Rekognition: {e}")
```
```

Rekognition - Invalid ParameterException problem

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