Class: PSD::Image

Inherits:
Object
  • Object
show all
Includes:
Export::PNG, PSD::ImageFormat::RAW, PSD::ImageFormat::RLE, PSD::ImageMode::CMYK, PSD::ImageMode::Greyscale, PSD::ImageMode::RGB
Defined in:
lib/psd/image.rb,
lib/psd/image_exports/png.rb

Overview

Parses the full preview image at the end of the PSD document.

Direct Known Subclasses

ChannelImage

Defined Under Namespace

Modules: Export

Constant Summary collapse

COMPRESSIONS =

All of the possible compression formats Photoshop uses.

[
  'Raw',
  'RLE',
  'ZIP',
  'ZIPPrediction'
]

Instance Method Summary collapse

Methods included from Export::PNG

#save_as_png, #to_png

Constructor Details

#initialize(file, header) ⇒ Image

Store a reference to the file and the header. We also do a few simple calculations to figure out the number of pixels in the image and the length of each channel.



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# File 'lib/psd/image.rb', line 21

def initialize(file, header)
  @file = file
  @header = header

  @num_pixels = width * height
  @num_pixels *= 2 if depth == 16

  calculate_length
  @channel_data = {} # Using a Hash over an NArray, because NArray has problems w/ Ruby 2.0. Hashes are faster than Arrays

  @start_pos = @file.tell
  @end_pos = @start_pos + @length

  @pixel_data = []

  PSD.logger.debug "Image: #{width}x#{height}, length = #{@length}, mode = #{@header.mode_name}, position = #{@start_pos}"

  # Each color channel is represented by a unique ID
  @channels_info = [
    {id: 0},
    {id: 1},
    {id: 2},
    {id: -1}
  ]
end

Instance Method Details

#parse ⇒ Object

Begins parsing the image by first figuring out the compression format used, and then by reading the image data.



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# File 'lib/psd/image.rb', line 49

def parse
  @compression = parse_compression!

  # ZIP not implemented
  if [2, 3].include?(@compression)
    PSD.logger.debug "Warning: ZIP image compression not supported yet. Skipping."
    @file.seek @end_pos and return
  end

  PSD.logger.debug "Compression: id = #{@compression}, name = #{COMPRESSIONS[@compression]}"

  parse_image_data!

  return self
end