Jain Art of India
The principal themes which found expression in the art of Jainism are presented, notably the role of the Jina image, the significance of the deities, the ritual and narrative role of the illustrated text, and the Jain cosmology as seen through cosmological paintings. The place of pilgrimage in the Jain tradition is illustrated through monumental pilgrimage paintings.
There is much in the historical development of Jain art which has parallels in the religious art of both Hinduism and Buddhism, but there are other aspects, particularly in relation to the role of the image in worship.
The creation of the Jina image is among the earliest recorded figurative representations in Indian art. Inscriptional references from the 3rd century BC record the worship of Jina images. Archaeological evidence makes it clear that images were in demand from an early period: certainly image worship was well established in the Kushan period (1st-3rd century AD). Inscriptions from this period record that monks were encouraging members of the laity to commission images of the Jinas, possibly following the Buddhist practice of performing meritorious acts. Inscribed sculptures survive from both Mathura and Allichatra recording this patronage, much of which was undertaken by female laity and nuns. For example, an inscribed 2nd century Jina image in the exhibition was commissioned by a female lay devotee named Datta on the advice of her teacher and installed in AD 157 at the Vodva stupa, Kankali Tila, Mathura. An early text the Padmacarita of AD 473 extols the merits of building Jina-bhavanas (image houses) and installing images of Jina, though this practice was not uni- versally welcomed by all early Jain teachers. These dissenting voices were troubled by the inherent contradiction between image worship and Jain orthodox teachings: the Jina is a liberated soul, freed of its material body and resides in the celestial abode, represented as the heavenly assembly hall (samavasarana). As such the Jina is no longer of this world and is incapable of being represented. It could be argued that the truest representation of a Jina is the representation as a silhouette out-out, a positive void.
It is a magical diagram yantra of a perfected being or siddha. Despite this professed "emptiness" of images of the Jina, they nonetheless are designed following strict iconographic (i.e. symbolic) and iconometric systems.
The latter system prescribes the measurements and proportions of images. It is the strict observance of these conventions, laid down in sastras (technical manuals) which account for the remarkable degree of uniformity in Jain images. It is prescribed in Hindu silpa sastras that an image (painted or sculptured, citra or murti) must have an inner life force, prana. Although not required theologically, Jain images often display this quality of inner breath or life.
The strict rules of measurement and proportion are clearly illustrated by the 12th C. seated Santinatha from the V&A (Fig. 1). This remarkable large-scale, solid-cast image depicts the 16th Jina enthroned on a jewelled cushion and surrounded by celestial attendants. He sits in a yogic meditation posture, with his hands gently resting, one on the other. Iconometric drawings used by artists in the preparation of Jina images reveal the standardization of the meditating Jina. Identification of a particular Jina is only made through the cognizant mark usually depicted on the base of the image. The standardization of Jina images is such that most Jinas cannot otherwise be distinguished.
Although all Jinas are of equal standing in Jainism, it is clear from the ratio of extant images of different Jinas that some attracted greater devotion than others. Santinatha is an obvious example, much venerated both by monks (as the preserver of Jainism at a time when it was in danger of extinction) and by the laity who turn to him as the Jina most associated with averting calamities and ensuring calm in the world - as his name suggests: santi = "peace", natha = "lord". Only two Jinas are physically distinguishable from the other 22 without the aid of their cognazant marks, namely Rishabbanatha, the first Jina, recognizable by his uncut hair, and Parsvanatha, the 23rd tirtankara, always represented with a cobra canopy.

Jainism has a second theological difficulty with image worship. The Jinas were intended to serve as reminders to the faithful of the possibility of liberation; i.e., they served as role models for both the Jain laity, guiding their ethical code of living, and for the aspirant Jina, providing inspiration and a reminder that spiritual liberation is an attainable goal. As a detached soul, removed from this world, the Jina is incapable of responding to a devotee's prayers or requests. This inability to be interventionist, to respond to the prayers and offerings from the faithful, sets Jina images apart from both all Hindu and most Buddhist deities, who can be called upon to ritually correct approaches by a devotee.
Source : http://www.mahavir.com/jainismidolshis.htm