No resolution for esponscan2 and imagescan2

The backends epsonscan2 and imagescan2 return an interval.
xsane does not know how to process it.
Here is the output of scanimage for the Epson ET-2750 :

All options specific to device `imagescan:esci:usb:/sys/devices/pci0000:00/0000:00:15.0/usb1/1-2/1-2:1.0':
  General:
    --source Document Table [Document Table] [read-only]
        Document Source
    --enable-resampling[=(yes|no)] [inactive]
        This option provides the user with a wider range of supported
        resolutions.  Resolutions not supported by the hardware will be
        achieved through image processing methods.
    --resolution 50..1200dpi [75]
        Resolution
    --resolution-bind[=(yes|no)] [yes]
        Bind X and Y resolutions
    --x-resolution 50..1200dpi [75] [read-only]
        X Resolution
    --y-resolution 50..1200dpi [75] [read-only]
        Y Resolution
    --scan-area Executive/Portrait|ISO/A4/Portrait|ISO/A5/Portrait|ISO/A5/Landscape|ISO/A6/Portrait|ISO/A6/Landscape|JIS/B5/Portrait|JIS/B6/Portrait|JIS/B6/Landscape|Letter/Portrait|Manual|Maximum [Manual]
        Scan Area
    --mode Monochrome|Grayscale|Color [Color]
        Image Type
  Geometry:
    -x 0..215.9mm [215.9]
        Width of scan-area.
    -y 0..297.18mm [297.18]
        Height of scan-area.
    -l 0..215.9mm [0]
        Top Left X
    -t 0..297.18mm [0]
        Top Left Y
  Enhancement:
    --rotate 0 degrees|90 degrees|180 degrees|270 degrees|Auto [0 degrees]
        Rotate
    --blank-threshold 0..100 [0]
        Skip Blank Pages Settings
    --brightness -100..100 [0]
        Change brightness of the acquired image.
    --contrast -100..100 [0]
        Change contrast of the acquired image.
    --threshold 0..255 [128]
        Threshold
  Other:
    --gamma 1.0|1.8 [1.8]
        Gamma
    --jpeg-quality 1..100 [90]
        JPEG Quality
    --transfer-format JPEG|RAW [RAW]
        Selecting a compressed format such as JPEG normally results in faster
        device side processing.
    --transfer-size 1..268435455 [1048576]
        Transfer Size