HPLIP

only 300 dpi available scanning HP OJP 7740

Asked by Thomas Hunter

When scanning using HPLIP and xsane, 300 dpi is the highest resolution offered. Spec says that 1200 is available on the Officejet Pro 7740. Touchscreen allows 600 dpi. Usually 300 dpi is plenty, but to scan old photos and enlarge them higher resolution would be desirable. I don't understand why there should be what appears to be an arbitrary limit of 300 dpi..

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Thomas Hunter
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Thomas Hunter (tshunter001) said : 		#1

Suddenly, I have 1200 dpi scanning. I don't think that I did anything more than just doing another try. I do get a message that says: "Backend sends more image data than it defined in parameters", but I've had that before with other scanners.

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Serg (sergey-adamovski) said (last edit ): 		#2

I had the same problem with gscan2pdf. The solution is:
- Switch "scan source" to anything other than "Flatbed" (e.g. "ADF" or "Duplex")
- Switch "scan source" back to "Flatbad"
- Choose the resolution you want (75, 100, 200, 300, 600 or 1200 ppi)
- Do this every time you start gscan2pdf.

By the way, xsane 0.999 looks to show all resolutions from the beginning.

Background:
Some people at HP think ADF unit is so bad that it makes no sense to use any resolution above 300 ppi. Therefore they allow higher resolutions only when you "select" the "Flatbad" source. To be able to tell the scanner driver you select this source (which is selected by default), you have first to select some different. Probably this is a bug in the driver implementation, because if you ask the driver with "scanimage -A", you get only resolutions up to 300 ppi.