1. Field of the Invention
The present invention concerns a transfer material for use in thermal transfer which is useful for forming transfer images of a desired tone, as well as a method of forming thermal transfer images of a desired tone by using the transfer material.
The present invention further relates to a method of forming images of sepia tone by laminating a laminate film colored to the sepia tone over images formed on a hard copy by an optional method, thereby obtaining a hard copy of the sepia tone.
2. Description of Related Art
An image forming method by thermal transfer process of heating an ink ribbon by a thermal head of the like in accordance with image information, transferring a dye from the ink ribbon to a material undergoing image transfer material such as a sheet of photographic paper (hereinafter referred to as a transfer material) by means of heat melting or thermal diffusion and forming images on the transferred material has been adopted generally. In particular, an image forming method by a subliming thermal transfer process for forming thermal transfer images by using an ink ribbon having an ink layer comprising a subliming or heat diffusing dye has been noted in recent years as a method of preparing a hard copy of video images since full color photographic images of a continuous gradation can be formed.
By the way, transfer materials used for forming images in the thermal transfer process have been formed so as to exhibit a white color. This is because better color reproducibility can be provided to images as an output sheet of a hard copy. If the transfer material exhibits a color other than white, full color or black and white photographic-images can not be formed at a good color reproducibility.
On the other hand, it has also been desired to provide images with various refined appearance in recent years. For example, since photographs discolored to a sepia tone provides a feeling of elapse of long years, sepia tone photographs have been prepared artificially by applying a special treatment to silver salt photographic paper and displayed and sold then in theme parks such as Western village. Further, in a case of forming sepia tone images by the thermal transfer process, the tones of images outputted to a printer are adjusted to the sepia tone by using soft wares in the printer or soft wares of a host computer to a digital printer. That is, in a video printer, since input signals are usually video signals such as NTSC composite, S-Video or RGB composite signals, it is difficult to convert image data into those of the sepia tone. Then, the outputted images are converted into the sepia tone by changing the soft wares in the printer and providing a print density curve used exclusively for the sepia tone. Further, in a digital printer, images on the connected host computer are previously converted into the sepia tone by the soft wares of the host computer and then the data are transferred to the printer.
However, among the existent methods for forming sepia tone images, a method of preparing the sepia tone photographs by applying a special treatment to a silver salt photographic paper involves a problem with respect to the toxicity of a solution for the treatment or the post-treating method.
Further, a method of forming sepia tone images by the thermal transfer or ink jet process, by softwares in the printer or soft wares of the host computer for the digital printer involves a problem that replacement of soft wares is difficult between a case of forming images of usual tones and a case of forming images of the sepia tone.