The present day digital camera includes many functions. For example, there is known a digital camera which has a character photographing mode in addition to a normal photographing mode. The normal photographing mode is the mode in which ordinary snapshots, for example, photographs of scenery are taken. In the character photographing mode, the digital camera subjects data to image processing so as to improve the appearance of the characters.
There is a digital still camera disclosed in Japanese patent application laid open No. HEI 08-125870. This digital still camera has a structure as follows. The digital still camera has the normal photographing mode and the document photographing mode. Any one of these two modes can be selected. When the normal photographing mode is selected, image data is compressed by a natural picture compression unit. Whereas image data is compressed by a document compression unit (a compression method appropriate for an image with a small number of gray levels in achromatic color) when the document photographing mode is selected. The compressed image data is then stored in an externally provided memory. Therefore, the image data can efficiently be compressed irrespective of whether the data belongs to a picture or belongs to a photograph of a document without degradation in image quality.
However, the conventional type of digital camera has a problem that the data of the captured image can not effectively be used. More specifically, the digital camera having the character photographing mode can not transmit the captured image as through a facsimile. In order to transmit the image as a facsimile, following process is carried out. First, the image is transmitted to a computer where the image is subjected to processing such as expansion, image conversion, compression, or the like and then only the image can be transmitted as a facsimile.
Further, in the digital still camera described above, the compression method is uniquely determined based on the photographing mode. For example, when a document (for example, an encyclopedia) which contains picture of scenery is photographed, and if the picture is photographed in the document mode, the image data is compressed by the compression method suitable for an image with a small number of gray levels in achromatic color. Resultantly, the picture of the scenery can not be reproduced properly. Therefore, the user is required to photograph the same document in the normal photographing mode. Thus, the user has to choose the photographing modes based on the purpose of using the document.