resolutions of Epson 1270

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What is the spatial resolution of the Epson 1270 when printing on photo
glossy paper? What number of density levels can be printed in cyan,
magenta, blue, and grey by the Epson 1270 on photo glossy paper? Has anyone
experimented with this or has this information been published?

Charles P. Lamb
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More about resolutions epson 1270
  1. Archived from groups: comp.periphs.printers (More info?)

    In article <88SdnUHXw5Za5wjcRVn-pg@comcast.com>, Charles P Lamb
    <clamb@acm.org> writes
    >What is the spatial resolution of the Epson 1270 when printing on photo
    >glossy paper? What number of density levels can be printed in cyan,
    >magenta, blue, and grey by the Epson 1270 on photo glossy paper? Has anyone
    >experimented with this or has this information been published?
    >
    Epson have published lots of technical information about the benefits of
    their printers in their patents, but it is never clear which patents
    dominate or limit the potential of any particular device. Thus, soon
    after buying a 1270, when it was introduced, I started a series of
    tests, the results of which have been confirmed by others in due course.

    The printer operates a stochastic dither process which dynamically
    trades spatial resolution and the tonal fidelity on the image for
    optimum results. Like all other Epson desktop printers, irrespective of
    the dot resolution, the maximum spatial resolution of the image is
    defined by the printer driver, which resamples to 720ppi, and this is
    just resolvable on Premium Glossy Paper under magnification, the
    microporse structure of which restricts lateral diffusion. So 360cy/in,
    or about 14cy/mm, is the limiting resolution of the printer - which is
    true of all Epson desktop printers irrespective of their advertised
    resolution. The advertised resolution states how many ink dots can be
    placed per inch, not how many pixels per inch can be rendered.

    The 1270 printer itself has six inks, Yellow, Magenta, Cyan, Light
    Magenta, Light Cyan and Black, and it can place these inks on a dot
    matrix which is 1440dpi x 720dpi. Consequently there can be two dots of
    ink placed in each of the highest resolution pixel cells. In addition,
    each ink dot can have 3 different sizes, large, medium and small, and
    this also changes the amount of ink in each resolution pixel cell.
    Combining mixes of light ink, black ink, no ink, and full ink in the 3
    sized drops that can be placed in the two available dots per pixel
    yields a maximum of 45 shades of Cyan and Magenta, but only 18 shades of
    yellow/brown (ignoring the pure black and white combinations, but using
    black and white 'dots' to change the average density. Not all of these
    shades are actually used however, because many of them are combinations
    of light and dark inks that are very close to each other, so perhaps
    only half this number are available.

    The algorithm used for the ink droplet placement knows what the shade of
    each combination of dots is and, for each pixel can work out the
    difference between what is placed and what should be placed. This
    difference, or error, is then distributed around the 4 of the nearest 8
    pixels that have not yet been printed to adjust the colour that they
    should be printed at. Thus if there is a large area of colour which is
    almost the same, but not accurately represented by the shades available
    in the pixel, it can be achieved by more averaging the error out over
    many pixels. However if there is fine structure in the image then the
    exact colour of each pixel in that structure is less important and the
    structure can be represented quite accurately as well.

    So the real answer to all of your questions about resolution and number
    of colours available is that it really does depend on the image content
    - fine details are represented with less colours than large areas and
    the printer algorithm dynamically adjusts the resolution and colour
    depending on the image content.
    --
    Kennedy
    Yes, Socrates himself is particularly missed;
    A lovely little thinker, but a bugger when he's pissed.
    Python Philosophers (replace 'nospam' with 'kennedym' when replying)
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