image utils

gistfile1.txt

# 1. CROP SQUARE
# Usage: img_sq input.jpg
# Description: Crops the image to the largest possible center square.
# Output: input_sq.png
img_sq() {
  local input="$1"
  if [ -z "$input" ]; then echo "Usage: img_sq <input_file>"; return 1; fi
  
  local filename="${input%.*}"
  ffmpeg -i "$input" -vf "crop=w=min(iw\,ih):h=min(iw\,ih)" "${filename}_sq.png"
}

# 2. CROP CIRCLE
# Usage: img_circ input.jpg
# Description: Crops center square, then applies a circular mask with anti-aliasing (smooth edges) and transparency.
# Output: input_circle.png
img_circ() {
  local input="$1"
  if [ -z "$input" ]; then echo "Usage: img_circ <input_file>"; return 1; fi
  
  local filename="${input%.*}"
  # Filter explanation:
  # 1. crop=...          -> Cut the square
  # 2. format=rgba       -> Add alpha channel
  # 3. geq=...           -> Calculate distance from center for every pixel. 
  #                         Uses 'clip' to create a soft anti-aliased edge.
  ffmpeg -i "$input" -vf "crop=w=min(iw\,ih):h=min(iw\,ih),format=rgba,geq=r='r(X,Y)':a='st(0,min(W,H)/2); st(1,hypot(X-W/2,Y-H/2)); clip((ld(0)-ld(1)+0.5),0,1)*255'" "${filename}_circle.png"
}

# 3. RESIZE (RATIO)
# Usage: img_scale input.jpg 0.5
# Description: Resizes the image by a multiplier (e.g. 0.5 = 50% size). Keeps aspect ratio.
# Output: input_x0.5.png
img_scale() {
  local input="$1"
  local ratio="$2"
  if [ -z "$ratio" ]; then echo "Usage: img_scale <input_file> <ratio>"; return 1; fi
  
  local filename="${input%.*}"
  ffmpeg -i "$input" -vf "scale=iw*${ratio}:-1" "${filename}_x${ratio}.png"
}

# 4. SMART CONVERT
# Usage: img_convert input.png webp  OR  img_convert input.png output.jpg
# Description: Converts formats. If second arg is just an extension (e.g. 'webp'), it auto-names the file.
# Output: input.webp OR output.jpg
img_convert() {
  local input="$1"
  local dest="$2"

  if [ -z "$dest" ]; then
    echo "Usage: img_convert <input_file> <extension_or_filename>"
    return 1
  fi

  # Smart Check: If $dest has no dot (e.g. "webp"), treat it as an extension
  # and auto-generate the filename based on the input name.
  if [[ "$dest" != *.* ]]; then
    local filename="${input%.*}"
    dest="${filename}.${dest}"
  fi

  # Optimization: If target is WebP, apply specific quality settings (q:v 80)
  if [[ "$dest" == *.webp ]]; then
     ffmpeg -i "$input" -c:v libwebp -q:v 80 "$dest"
  else
     ffmpeg -i "$input" "$dest"
  fi
}