sometimes referred to as "the" inventor of "the" halftone process, but this is incorrect and Ives never made such a claim for himself. There was not one halftone process, but a considerable number of them, the earliest dating nearly as far back as the introduction of practical photography in 1839. They varied widely in their degree of practicality and the quality of their results. The first attempts involved directly etching the unique images formed on metallic Daguerreotype plates. Although pleasing results were obtained, etching the plates required great skill and care, the images could not be printed along with ordinary type, and the delicate plates wore out after a very small number of impressions, making such processes useless for publishing on a commercial scale. More practical processes started appearing in the 1860s, but high cost, special printing requirements or low image quality variously kept these early processes from coming into widespread use. Ives turned his attention to halftone processes in the late 1870s. The objectives were to more or less automatically convert the intermediate tones of a photographic image into small lines or dots of stark black and white; to do this better, or at least more efficiently, than was possible with existing processes; and to create a printing block that could be combined with blocks of text in an ordinary printing press. The lines or dots, of varying widths or sizes respectively, had to be small enough to adequately blend together in the eye at a normal viewing distance, producing the illusion of various shades of gray, yet the printing plates had to be durable enough to last through a typical press run without excessive degradation. Above all, the process had to be economical enough to make its widespread commercial use practical. Ives patented his first "Ives' process" in 1881. This early process required the creation of a photographic relief image, made by a variety of the carbon process, from which a plaster cast was made. The highest areas on the surface of the plaster corresponded with the darkest areas of the original photograph. The cast was pressed into contact with an inked rubber grid consisting of an array of tiny pyramidal elements, which caused a regular array of ink dots to be deposited on the plaster, their sizes varying according to the heights of the surface. The dot pattern was then photographed onto a metal plate coated with