Re: [BUG] Epson 1640SU, xsane preview problem]

From: Jean-Luc Coulon (jean-luc.coulon@wanadoo.fr)
Date: Fri May 25 2001 - 05:10:01 PDT

  • Next message: Matto Marjanovic: "Re: Problem with Microtek 35t slide/negative scanner"

    Hi (re!) Oliver,

    Oliver Rauch wrote:
    >
    > Jean-Luc Coulon wrote:
    >
    > > > if (quality <= min_quality+20)
    > > >
    > > With this change, it works !
    >
    > Fine. Although this is not the correct way to solve it.
    I can imagine...
    >
    > >
    > > Now, back to the "resize" function.
    > > Basically it works : I was confused with the previous problem.
    > > But the "autoselect" button does not work as expected.
    > >
    > > If I place a drawind in the middle of the bed, any size selected, only
    > > the bottom line is at the right place, the other ones are at the
    > > top/left/right ends of the format.
    > >
    > > Why is the color set to 25 instead of 55 in xsane-preview.c, line 5505 ?
    > > (this has no effect for my problem)
    >
    > Does your scanner use a black or a white background or anything else?
    >

    The background is white. I've done the test with a red square of paper
    in the middle of the back.

    > The 25 is a bug, I will replace it by 55.
    Ok
    >
    > The routine does search pixels that differ from the background. The backround
    > has to be black or white. When one pixel is found that differs with a brightness
    > of about 20% of the visible range the frame position is found.
    >
    > The test is done with the gamma corrected preview, so you will get different results
    > with different gamma/brightness/contrast settings.
    >
    I've done tests with different gamma/brightness/contrast settings, the
    results is always the same. The bottom line is ok. If I move my
    document, sometimes, the top line is not at the top of the window but
    somewhere at about 2cm fro the document. I've never seen the left and
    right line to move.

    Here is a small part of a trace, do you want more ?
    [xsane] xsane_back_gtk_unit_string
    [xsane] xsane_update_histogram
    [xsane] xsane_update_histogram
    [xsane] preview_autoselect_scanarea
    [xsane] preview_autoselect_scanarea: average margin brightness is 189
    [xsane] preview_autoselect_scanarea: background is white
    [xsane] preview_get_scale_device_to_image: scale = 1.965139, 1.965139
    [xsane] preview_draw_selection
    [xsane] preview_draw_rect [0.51 0.51 215.25 169.96]
    [xsane] preview_transform_coordinates_device_to_window
    [xsane] preview_get_scale_device_to_window: scale = 1.292265, 1.292265
    [xsane] preview[0.51 0.51 215.25 169.96] -> window[0.66 0.66 278.16
    219.64]
    [xsane] preview_draw_rect [0.51 0.51 215.25 164.36]
    [xsane] preview_transform_coordinates_device_to_window
    [xsane] preview_get_scale_device_to_window: scale = 1.292265, 1.292265
    [xsane] preview[0.51 0.51 215.25 164.36] -> window[0.66 0.66 278.16
    212.40]
    [xsane] preview_establish_selection
    [xsane] preview_order_selection
    [xsane] preview_rotate_previewsurface_to_devicesurface(rotation = 0)
    [xsane] preview[0.51 0.51 215.25 164.36] -> device[0.51 0.51 215.25
    164.36]
    [xsane] preview_set_option_float

    -----
    Regards
                    Jean-Luc

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