Device, method, and program for compressing image data

A non-transitory computer-readable storage medium containing a program for compressing input image data, the input image data targeted to be compressed being rectangle-shaped image data having a length of X0 in a long side and a length of Y0 in a short side, which when loaded into a memory and run by a computer, causes the computer to execute:

• resizing of the input image data by reducing the X0 and Y0 lengths to a size defined in advance to generate primary compression image data and primary compression information showing an image surface area A1 and an image capacity W1 of the primary compression image data;
• and
• compressing the primary compression image data to generate secondary compression image data by calculating a length x of a long side of the secondary compression image data by applying the image surface area A1 and the image capacity W1 of the primary compression image data, and an aspect ratio AR (Y0/X0) of the input image data targeted to be compressed into the following expression:
• x=·((A1·D)/(AR·W1)),
• wherein D is a compression target capacity value of the secondary compression image data;
• wherein the image surface area A1 of the primary compression image data is larger than an image surface area of the secondary compression image data.

A method of compressing image data, the method comprising:

• using rectangle-shaped input image data having a length of X0 in a long side and a length of Y0 in a short side as image data targeted to be compressed;
• resizing the input image data by reducing the X0 and Y0 lengths to a size defined in advance to generate primary compression image data and primary compression information showing an image surface area A1 and an image capacity W1 of the primary compression image data;
• and
• compressing the primary compression image data to generate secondary compression image data by calculating a length x of a long side of the secondary compression image data by applying the image surface area A1 and the image capacity W1 of the primary compression image data, and an aspect ratio AR (Y0/X0) of the input image data targeted to be compressed into the following expression:
• x=√((A1·D)/(AR·W1)),
• wherein D is a compression target capacity value of the secondary compression image data;
• wherein the image surface area A1 of the primary compression image data is larger than an image surface area of the secondary compression image data.