Image Processing MCP Server

Instructions

Implementation Reference

• tools/color_adjust.py:506-579 (handler)

  Core handler function implementing the gamma adjustment logic. Validates inputs, loads image using ImageProcessor, applies gamma correction via lookup table and PIL's point() method for RGB/L/ other modes, processes output, and returns JSON result.

  async def adjust_gamma(image_source: str, gamma: float) -> list[TextContent]:
      """
      调整图片伽马值
      
      Args:
          image_source: 图片数据（base64编码）或文件路径
          gamma: 伽马值（0.1-3.0）
          
      Returns:
          调整后的图片数据
      """
      try:
          # 验证参数
          if not image_source:
              raise ValidationError("图片数据不能为空")
          
          if not validate_numeric_range(gamma, 0.1, 3.0):
              raise ValidationError(f"伽马值必须在0.1-3.0范围内: {gamma}")
          
          # 加载图片
          image = processor.load_image(image_source)
          
          # 创建伽马校正查找表
          gamma_table = [int(((i / 255.0) ** (1.0 / gamma)) * 255) for i in range(256)]
          
          # 应用伽马校正
          if image.mode == 'RGB':
              # 对RGB图片分别处理每个通道
              r, g, b = image.split()
              r = r.point(gamma_table)
              g = g.point(gamma_table)
              b = b.point(gamma_table)
              gamma_image = Image.merge('RGB', (r, g, b))
          elif image.mode == 'L':
              # 对灰度图直接处理
              gamma_image = image.point(gamma_table)
          else:
              # 其他模式先转换为RGB
              rgb_image = image.convert('RGB')
              r, g, b = rgb_image.split()
              r = r.point(gamma_table)
              g = g.point(gamma_table)
              b = b.point(gamma_table)
              gamma_image = Image.merge('RGB', (r, g, b))
          
          # 输出处理后的图片
          output_info = processor.output_image(gamma_image, "gamma")
          
          result = {
              "success": True,
              "message": f"伽马调整成功: 伽马值 {gamma}",
              "data": {
                  **output_info,
                  "gamma_value": gamma,
                  "original_mode": image.mode,
                  "size": image.size
              }
          }
          
          return [TextContent(type="text", text=json.dumps(result, ensure_ascii=False))]
          
      except ValidationError as e:
          error_result = {
              "success": False,
              "error": f"参数验证失败: {str(e)}"
          }
          return [TextContent(type="text", text=json.dumps(error_result, ensure_ascii=False))]
          
      except Exception as e:
          error_result = {
              "success": False,
              "error": f"伽马调整失败: {str(e)}"
          }
          return [TextContent(type="text", text=json.dumps(error_result, ensure_ascii=False))]

• main.py:458-472 (registration)

  Tool registration via @mcp.tool() decorator in FastMCP server. Defines input schema using Pydantic Annotated fields and provides a synchronous wrapper that calls the async handler from color_adjust module using safe_run_async.

  @mcp.tool()
  def adjust_gamma(
      image_source: Annotated[str, Field(description="图片源，可以是文件路径或base64编码的图片数据")],
      gamma: Annotated[float, Field(description="伽马值，1.0为原始，>1.0变亮，<1.0变暗", gt=0)]
  ) -> str:
      """调整图片伽马值"""
      try:
          result = safe_run_async(color_adjust_gamma(image_source, gamma))
          return result[0].text
      except Exception as e:
          return json.dumps({
              "success": False,
              "error": f"调整伽马值失败: {str(e)}"
          }, ensure_ascii=False, indent=2)

• tools/color_adjust.py:119-138 (schema)

  Explicit Tool schema definition for adjust_gamma in get_color_adjust_tools(), matching the registered input parameters (though not directly used in MCP registration).

  Tool(
      name="adjust_gamma",
      description="调整图片伽马值",
      inputSchema={
          "type": "object",
          "properties": {
              "image_source": {
                  "type": "string",
                  "description": "图片数据（base64编码）或文件路径"
              },
              "gamma": {
                  "type": "number",
                  "description": "伽马值（0.1-3.0，1.0为原始值）",
                  "minimum": 0.1,
                  "maximum": 3.0
              }
          },
          "required": ["image_source", "gamma"]
      }
  ),