EviScene / eviscene /tools /count_objects.py
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"""Count visible objects with schema-constrained vision output."""
from __future__ import annotations
import math
import os
import tempfile
from dataclasses import dataclass, field
from typing import Any, Dict, Optional
from eviscene.integrations.gemini import RUNTIME_METRICS_KEY, exception_runtime_metrics
from eviscene.tools.base import BaseTool
COUNT_PROMPT_TEMPLATE = """\
You are the object-counting module of an image verification system.
Count only the visible instances of the requested target.
Target: {target_object}
Rules:
1. Inspect the full supplied image or crop systematically.
2. Count a partially occluded instance only when its presence is visually supported.
3. Return zero when no target instance is visible.
4. Do not infer instances outside the frame or hidden behind objects.
5. Keep the explanation literal and concise.
6. Return exactly one JSON object matching the response schema.
"""
COUNT_RESPONSE_SCHEMA: Dict[str, Any] = {
"type": "object",
"properties": {
"target": {"type": "string", "maxLength": 200},
"count": {"type": "integer", "minimum": 0},
"confidence": {"type": "number", "minimum": 0.0, "maximum": 1.0},
"details": {"type": "string", "maxLength": 800},
"locations": {
"type": "array",
"items": {"type": "string", "maxLength": 240},
"maxItems": 50,
},
},
}
@dataclass
class CountObjectsTool(BaseTool):
"""Count a requested visible object in the image or a normalized crop."""
name: str = "count_objects"
description: str = (
"Count a specific visible object in the image or in a normalized crop. "
"Provide a precise target such as 'fingers on the left hand' or "
"'people in the background'. Returns a count, confidence, and locations."
)
parameters: dict = field(
default_factory=lambda: {
"type": "object",
"properties": {
"image_input": {
"type": "string",
"description": "Local path to the image file.",
},
"target_object": {
"type": "string",
"description": "A precise description of what to count.",
},
"bbox": {
"type": "array",
"items": {"type": "number"},
"minItems": 4,
"maxItems": 4,
"description": (
"Optional normalized crop [x1, y1, x2, y2], with every "
"coordinate in [0, 1]."
),
},
"visual_question_id": {"type": "string"},
"source_evidence_id": {"type": "string"},
"source_discovery_id": {"type": "string"},
"expected_property": {"type": "string"},
},
"required": ["image_input", "target_object"],
}
)
client: Optional[Any] = field(default=None, repr=False)
provider: str = "gemini"
model_name: str = "gemini-3.7-flash"
def _get_client(self) -> Any:
if self.client is None:
from eviscene.integrations.vlm.factory import build_vlm_client
self.client = build_vlm_client(
provider=self.provider,
model_name=self.model_name,
)
return self.client
def call(self, params: Dict[str, Any]) -> Dict[str, Any]:
image_input = str(params.get("image_input", "")).strip()
target_object = str(params.get("target_object", "")).strip()
if not image_input:
return {"status": "error", "error": "image_input is required."}
if not target_object:
return {"status": "error", "error": "target_object is required."}
actual_image = image_input
temporary_path: Optional[str] = None
bbox = params.get("bbox")
if bbox is not None:
try:
coordinates = self._validate_bbox(bbox)
actual_image, temporary_path = self._crop(image_input, coordinates)
except Exception as exc:
return {
"status": "error",
"error": f"Requested count region could not be cropped: {exc}",
}
try:
parsed = self._get_client().create_image_json(
system_prompt=COUNT_PROMPT_TEMPLATE.format(
target_object=target_object,
),
user_text=f"Count the visible instances of: {target_object}",
image_input=actual_image,
max_tokens=1000,
model_name=self.model_name,
response_schema=COUNT_RESPONSE_SCHEMA,
)
except Exception as exc:
error = {
"status": "error",
"error": f"Counting failed: {type(exc).__name__}: {exc or '<no message>'}",
}
metrics = exception_runtime_metrics(exc)
if metrics:
error[RUNTIME_METRICS_KEY] = metrics
return error
finally:
if temporary_path:
try:
os.remove(temporary_path)
except OSError:
pass
result = self._validate_response(parsed, target_object)
runtime_metrics = parsed.get(RUNTIME_METRICS_KEY)
if runtime_metrics:
result[RUNTIME_METRICS_KEY] = runtime_metrics
return result
@staticmethod
def _validate_bbox(value: Any) -> tuple[float, float, float, float]:
if not isinstance(value, (list, tuple)) or len(value) != 4:
raise ValueError("bbox must contain exactly four normalized coordinates")
if any(isinstance(item, bool) or not isinstance(item, (int, float)) for item in value):
raise ValueError("bbox coordinates must be numeric")
coordinates = tuple(float(item) for item in value)
if any(not math.isfinite(item) or item < 0.0 or item > 1.0 for item in coordinates):
raise ValueError("bbox coordinates must be finite values in [0, 1]")
x1, y1, x2, y2 = coordinates
if x1 >= x2 or y1 >= y2:
raise ValueError("bbox must satisfy x1 < x2 and y1 < y2")
return x1, y1, x2, y2
@staticmethod
def _crop(
image_input: str,
bbox: tuple[float, float, float, float],
) -> tuple[str, str]:
from PIL import Image
with Image.open(image_input) as image:
width, height = image.size
x1, y1, x2, y2 = bbox
pixel_box = (
max(0, min(int(x1 * width), width - 1)),
max(0, min(int(y1 * height), height - 1)),
max(1, min(int(math.ceil(x2 * width)), width)),
max(1, min(int(math.ceil(y2 * height)), height)),
)
if pixel_box[0] >= pixel_box[2] or pixel_box[1] >= pixel_box[3]:
raise ValueError("bbox resolves to an empty crop")
cropped = image.crop(pixel_box)
handle, temporary_path = tempfile.mkstemp(prefix="count_objects_", suffix=".png")
os.close(handle)
try:
cropped.save(temporary_path)
except Exception:
try:
os.remove(temporary_path)
except OSError:
pass
raise
return temporary_path, temporary_path
@staticmethod
def _validate_response(parsed: Any, target_object: str) -> Dict[str, Any]:
if not isinstance(parsed, dict):
return {"status": "error", "error": "Counting response must be a JSON object."}
count = parsed.get("count")
if isinstance(count, bool) or not isinstance(count, int) or count < 0:
return {
"status": "error",
"error": "Counting response must contain a non-negative integer 'count'.",
}
confidence = parsed.get("confidence")
if isinstance(confidence, bool) or not isinstance(confidence, (int, float)):
return {
"status": "error",
"error": "Counting response must contain numeric 'confidence'.",
}
confidence = float(confidence)
if not math.isfinite(confidence) or not 0.0 <= confidence <= 1.0:
return {
"status": "error",
"error": "Counting confidence must be a finite value in [0, 1].",
}
details = parsed.get("details")
locations = parsed.get("locations")
if not isinstance(details, str):
return {"status": "error", "error": "Counting details must be a string."}
if not isinstance(locations, list) or any(
not isinstance(location, str) for location in locations
):
return {"status": "error", "error": "Counting locations must be an array of strings."}
return {
"status": "success",
"target": target_object,
"count": count,
"confidence": confidence,
"details": details.strip(),
"locations": [location.strip() for location in locations],
}