元の画像の上に、もう1枚の画像（ロゴや透かし）を重ねます。
Convert an image to JPG, PNG, WebP, GIF, BMP or TIFF.
Reduce image file size by re-encoding at a chosen quality.
Resize an image by width/height or percentage, keeping aspect ratio.
Rotate an image by an angle and/or flip it horizontally or vertically.
Crop an image to a rectangular region.
Add a text caption or watermark onto an image.