07-03-2015, 02:26 PM
Hi,
Often, diagrams will print in much worse quality than diagrams. In simple terms, when text is sent to a printer, it is sent at a very high resolution - perhaps 300 or 600 or even 1200 dots per inch. So even with a magnifying glass, the print will look clear and detailed.
Now, a screen has a much lower resolution - perhaps 72 dots per inch (it depends on screen size and resolution - this monitor has 1920 pixels across, and measures just under 20.5 inches, so that's about 93 dpi. It's probably 96dpi "officially").
Having looked at those numbers, you might see why something that looks good on the screen might not look so good on paper. A scanned in diagram that has been reduced in resolution to look acceptable on the screen will generally look a bit fuzzy on paper.
It gets a bit worse when you consider how printers make shades of grey. The ink (or toner) is black. So the only way to make grey is to print a pattern of black dots and leave white space around them. From a distance, the eye merges these dots and sees grey. The exact shade depends on the ratio of black dots to white paper. This effect used to be very obvious on old newspaper print from 30+ years back...
There is a good Wikipedia article about this process: http://en.wikipedia.org/wiki/Halftone
A high resolution printer than can print at 1000dpi will deploy this technique very effectively when given a high quality image as its starting point. Older printers that could only print at 300dpi gave reasonable results, but looking closely, one could usually see the dot patterns that made up the shades of grey.
Of course, this also applies to colour printing, where the half-toning is done with the 3 primaries as well as the black ink or toner.
All very interesting - perhaps! - but doesn't answer the question. In short, you've probably got the message about laser printers by now, but what to do about the HP? How much effort it deserves might depend on how much ink you've got left to play with
One thing that occurred to me earlier:
The advice in post #2 is good, but the initial steps might not be correct if you haven't installed the whole suite of HP software. You should be able to find the options to clean the print heads and print test pages from the print driver alone - and the print driver is the bare minimum needed to make it work - so the following should help:
On Windows 7:
Click Start, move across and click on "Devices and Printers"
A box appears which should show your printer. Right-click on it, and select "Printing Preferences"
Up pops another box which will have many different options, and the exact options will depend on the printer driver that Windows is using - therefore I can't be specific at this stage. But hunt around, and hopefully you'll find options to clean the print heads and more. Looking at the Canon printer I have here, I see a tab called "Maintenance", which offers all sorts of interesting options to play with.
It's interesting that the contents of the "Printing Preferences" box has come from the manufacturer, even though I've never attempted to install any Canon stuff on this machine - Microsoft has obtained the driver from Canon, made sure it is compatible with Windows 7, and then made it available as a driver that gets automatically installed when the printer is first connected. Same deal for my HP laser printer. So I'm sure that you'll have something similar, even if you haven't installed the HP "Toolbox" that Nick had in mind earlier.
Hope that helps,
Mark
Often, diagrams will print in much worse quality than diagrams. In simple terms, when text is sent to a printer, it is sent at a very high resolution - perhaps 300 or 600 or even 1200 dots per inch. So even with a magnifying glass, the print will look clear and detailed.
Now, a screen has a much lower resolution - perhaps 72 dots per inch (it depends on screen size and resolution - this monitor has 1920 pixels across, and measures just under 20.5 inches, so that's about 93 dpi. It's probably 96dpi "officially").
Having looked at those numbers, you might see why something that looks good on the screen might not look so good on paper. A scanned in diagram that has been reduced in resolution to look acceptable on the screen will generally look a bit fuzzy on paper.
It gets a bit worse when you consider how printers make shades of grey. The ink (or toner) is black. So the only way to make grey is to print a pattern of black dots and leave white space around them. From a distance, the eye merges these dots and sees grey. The exact shade depends on the ratio of black dots to white paper. This effect used to be very obvious on old newspaper print from 30+ years back...
There is a good Wikipedia article about this process: http://en.wikipedia.org/wiki/Halftone
A high resolution printer than can print at 1000dpi will deploy this technique very effectively when given a high quality image as its starting point. Older printers that could only print at 300dpi gave reasonable results, but looking closely, one could usually see the dot patterns that made up the shades of grey.
Of course, this also applies to colour printing, where the half-toning is done with the 3 primaries as well as the black ink or toner.
All very interesting - perhaps! - but doesn't answer the question. In short, you've probably got the message about laser printers by now, but what to do about the HP? How much effort it deserves might depend on how much ink you've got left to play with
One thing that occurred to me earlier:
The advice in post #2 is good, but the initial steps might not be correct if you haven't installed the whole suite of HP software. You should be able to find the options to clean the print heads and print test pages from the print driver alone - and the print driver is the bare minimum needed to make it work - so the following should help:
On Windows 7:
Click Start, move across and click on "Devices and Printers"
A box appears which should show your printer. Right-click on it, and select "Printing Preferences"
Up pops another box which will have many different options, and the exact options will depend on the printer driver that Windows is using - therefore I can't be specific at this stage. But hunt around, and hopefully you'll find options to clean the print heads and more. Looking at the Canon printer I have here, I see a tab called "Maintenance", which offers all sorts of interesting options to play with.
It's interesting that the contents of the "Printing Preferences" box has come from the manufacturer, even though I've never attempted to install any Canon stuff on this machine - Microsoft has obtained the driver from Canon, made sure it is compatible with Windows 7, and then made it available as a driver that gets automatically installed when the printer is first connected. Same deal for my HP laser printer. So I'm sure that you'll have something similar, even if you haven't installed the HP "Toolbox" that Nick had in mind earlier.
Hope that helps,
Mark
