Question

我使用 jfreesane 库为Windows编写了一个小型Java SANE客户端，它运行良好一段时间但是昨天我发现扫描仪出现问题 CanoScan LiDE 60 - 当使用＆＃34;灰度＆＃34;模式扫描图像有灰色背景，我不知道如何摆脱它。这就是我所说的：

我遇到了其他一些扫描仪的问题并通过调整对比参数解决了这个问题，但是CanoScan LiDE 60没有。以下是＆＃34; scanimage -A＆＃34; 输出的完整选项列表（我尝试了除 gamma-table 之外的所有颜色）：

All options specific to device `genesys:libusb:003:002':
  Scan Mode:
    --mode Color|Gray|Lineart [Gray]
        Selects the scan mode (e.g., lineart, monochrome, or color).
    --source Flatbed|Transparency Adapter [inactive]
        Selects the scan source (such as a document-feeder).
    --preview[=(yes|no)] [no]
        Request a preview-quality scan.
    --depth 8|16 [8]
        Number of bits per sample, typical values are 1 for "line-art" and 8
        for multibit scans.
    --resolution 1200|600|300|150|75dpi [75]
        Sets the resolution of the scanned image.
  Geometry:
    -l 0..218mm [0]
        Top-left x position of scan area.
    -t 0..299mm [0]
        Top-left y position of scan area.
    -x 0..218mm [218]
        Width of scan-area.
    -y 0..299mm [299]
        Height of scan-area.
  Enhancement:
    --custom-gamma[=(yes|no)] [no]
        Determines whether a builtin or a custom gamma-table should be used.
    --gamma-table 0..65535,... [inactive]
        Gamma-correction table.  In color mode this option equally affects the
        red, green, and blue channels simultaneously (i.e., it is an intensity
        gamma table).
    --red-gamma-table 0..65535,... [inactive]
        Gamma-correction table for the red band.
    --green-gamma-table 0..65535,... [inactive]
        Gamma-correction table for the green band.
    --blue-gamma-table 0..65535,... [inactive]
        Gamma-correction table for the blue band.
    --swdeskew[=(yes|no)] [no]
        Request backend to rotate skewed pages digitally
    --swcrop[=(yes|no)] [no]
        Request backend to remove border from pages digitally
    --swdespeck[=(yes|no)] [no]
        Request backend to remove lone dots digitally
    --despeck 1..9 (in steps of 1) [1]
        Maximum diameter of lone dots to remove from scan
    --swskip 0..100% (in steps of 1) [0]
        Request driver to discard pages with low numbers of dark pixels
    --swderotate[=(yes|no)] [no]
        Request driver to detect and correct 90 degree image rotation
  Extras:
    --lamp-off-time 0..60 [15]
        The lamp will be turned off after the given time (in minutes). A value
        of 0 means, that the lamp won't be turned off.
    --lamp-off-scan[=(yes|no)] [no]
        The lamp will be turned off during scan.
    --threshold 0..100% (in steps of 1) [50]
        Select minimum-brightness to get a white point
    --threshold-curve 0..127 (in steps of 1) [50]
        Dynamic threshold curve, from light to dark, normally 50-65
    --disable-dynamic-lineart[=(yes|no)] [no]
        Disable use of a software adaptive algorithm to generate lineart
        relying instead on hardware lineart.
    --disable-interpolation[=(yes|no)] [no]
        When using high resolutions where the horizontal resolution is smaller
        than the vertical resolution this disables horizontal interpolation.
    --color-filter Red|Green|Blue|None [None]
        When using gray or lineart this option selects the used color.
  Sensors:
  Buttons:
    --clear-calibration
        Clear calibration cache

这是一个有趣的事情：简单扫描（Linux扫描程序）以某种方式设法使用此扫描仪从图像中删除灰色：

我不确定它是否使用了一些扫描后处理，或者它是否知道如何告诉扫描仪有关对比度的信息。如果它是前者，是否有任何Java库可以消除这种灰色噪声？

Answer 1

经过一些测试，我最终得到了这个函数（对比公式取自here）：

public void processImage(BufferedImage bimg, int brightness, int contrast, int t_black, int t_white) {
        Color c;
        int r, g, b;
        float factor = (259f * (contrast + 255f)) / (255f * (259f - contrast));

        for (int x = 0; x < bimg.getWidth(); x++)
            for (int y = 0; y < bimg.getHeight(); y++) {
                c = new Color(bimg.getRGB(x, y));
                // apply brightness and contrast
                r = Math.round(factor * (c.getRed() - 128) + 128) + brightness;
                g = Math.round(factor * (c.getGreen() - 128) + 128) + brightness;
                b = Math.round(factor * (c.getBlue() - 128) + 128) + brightness;
                // limit to [0, 255] range
                r = Math.min(255, Math.max(0, r));
                g = Math.min(255, Math.max(0, g));
                b = Math.min(255, Math.max(0, b));
                // apply black and white thresholds
                if (r < t_black && g < t_black && b < t_black)
                    bimg.setRGB(x, y, 0);
                else if (r > t_white && g > t_white && b > t_white)
                    bimg.setRGB(x, y, 255 << 16 | 255 << 8 | 255);
                else
                    bimg.setRGB(x, y, r << 16 | g << 8 | b);
            }
    }

如何从扫描图像中删除灰色背景

1 个答案: