Re: Printer resolution (was: Re: posted *istD Samples)
John, Have you ever used a recent HP at its highest mode? I've got a 5500, but have not performed the test. Sharper 4x6, maybe? No. I print 8x10s (or larger, now) - I suspect I've got a pack of 6x4 paper somewhere, but I haven't used it in years. It's hard enough to come up with even 600dpi for an 8x10; 6MP from an *ist-D doesn't come close, and neither does the 10MP I get from my 2700ppi Nikon Coolscan III. Even a 4000ppi scan only just manages to get to 600dpi for a full-frame 10 print. I doubt if I'll ever come up with a 1200ppi source image. Mind you, as Herb points out, even 600ppi is probably pushing the limits of what is physically reproducible on paper media. I didn't choose the (600ppi) HP over the (360ppi) Epson because of resolution; I chose it because I'm concerned about clogging after periods of not being used, and I like the fact that the HP inkheads are in the cartridge, and so can be replaced easily. I was also swayed by the fact that HP now use the same cartridge in almost all their printers - I'm somewhat tempted by the tiny 6x4 printer, and it would be nice to be able to move over the cartridges from the big printer rather than having two sets of cartridges to worry about. If I do get one of those I might be able to try a 1200ppi print.
Re: Printer resolution (was: Re: posted *istD Samples)
Several people have commented on determining the appropriate image resolution to send to the printer. The Nov/Dec issue of Digital Photo Pro magazine http://www.digitalphotopro.com has an interesting article, MisInformation, Setting Printer DPI. Treading lightly, to avoid violating copyright, I'll just toss in a few of the author's key points. According to his discussions with printer manufactures, the common recommendation on image resolution being some even multiple of printer resolution doesn't mean much. Modern printers vary the printer resolution over the area of the print, so even if the fraction resolution idea worked, what number would you use for the fraction?. The author did a range of test prints at 180 through 360 ppi and several steps in between with both Canon and Epson printers. These were evaluated by the editors of the photo magazines at Werner, the publisher. Some thought they saw differences using a magnifier, but no one could place the photos in order; most could see no difference among the images, particularly at normal viewing distances. I get a kick out of a lot of this discussion. Most of the stuff we argue about is really in the category of gilding the lily. It's always fun to show a few 8x10's to a group of friends or coworkers. Most people instinctively hold them at arm's length or a bit closer and usually comment on the subject material. You can always tell the photographers in the group, they hold them within an inch of their nose and start looking for dots. It boils down to this, 240 to 360 ppi will probably give acceptable results with most images. On some images you may be able to get by with resolution as low as 150 ppi. The only way to determine if a particular image density works for your image and your printer is to try it out and see if it is acceptable. Just one more note, if you are looking for a really good reference on printing, try Mastering Digital Printing by Harald Johnson. http://www.dpandi.com See you later, gs
Re: Printer resolution (was: Re: posted *istD Samples)
the HP documentation says the hardware is adressable to 1200x1200 but you lose PhotoREt. you have to send no higher than 600dpi if you want the hardware to do it. any higher and you have to do it yourself. unless you write your own PCL3+ printer driver, you can't. That matches my interpretation. It's a genuine 600 ppi photo printer, (using PhotoRet IV to get around 8 bits of colour resolution per pixel), and the standard HP-supplied software driver also offers a 1200ppi mode (which presumably still has access to the 4800 dpi horizontal positioning, and some way of controlling the number of ink droplets being deposited), but all the calculations have to be done in software by the driver.
Re: Printer resolution (was: Re: posted *istD Samples)
'the optimum pixel resolution [of the printed image] should ideally be the printer dpi divisible by a whole number. The following pixel resolutions should be used [for a 1440/2880 printer] : 144, 160, 180, 240, 288, 320, 360.' So what are the consequences of simply ignoring this? I have never applied this rule and the 8-1/2 x 11 inch (A4) prints I get off my Epson 870 are, to my eyes, excellent. I generally try to ensure that I have near, at, or above 300 ppi when I print. I did, though, once make an 8-1/2 x 11 print at 180 ppi, and thought it was pretty good. Now I have Genuine Fractals, which I put to use for anything that will print at under 250 ppi. Joe
Re: Printer resolution (was: Re: posted *istD Samples)
if you are above then it just wastes processing. if below, you are not pushing the limits of the printer. Herb... - Original Message - From: Joseph Tainter [EMAIL PROTECTED] To: pdml [EMAIL PROTECTED] Sent: Saturday, November 01, 2003 12:46 PM Subject: Re: Printer resolution (was: Re: posted *istD Samples) 'the optimum pixel resolution [of the printed image] should ideally be the printer dpi divisible by a whole number. The following pixel resolutions should be used [for a 1440/2880 printer] : 144, 160, 180, 240, 288, 320, 360.' So what are the consequences of simply ignoring this? I have never applied this rule and the 8-1/2 x 11 inch (A4) prints I get off my Epson 870 are, to my eyes, excellent.
Re: Printer resolution (was: Re: posted *istD Samples)
if you are above then it just wastes processing. With the current generation of printers, it's getting pretty hard to have an image that's higher-resolution than the printer! My current HP is 600 dpi in normal mode, 1200 dpi in best quality. Even on 8.5x11 paper at 600 dpi that's 30+ megapixels - more than a 4000ppi scan can get from a 35mm frame. An 11x17 print at 1200 dpi would need an incredible 250 megapixels. I'm not sure even a 6x7 frame can deliver that amount of real data. So either there are a lot of large-format users out there, or the printer is no longer the resolution-limiting step in the process.
Re: Printer resolution (was: Re: posted *istD Samples)
as i noted in my previous message, the printer driver works at a given maximum resolution that is not the dpi resolution of the printer but a submultiple. in the case of the Epson printer drivers, it is fixed at 360 dpi. anymore more is wasted. the Canon and HP ones probably are 300 dpi, but that is a guess. the Epson information is in the developer's documents for the binary data stream sent to the printer. Herb... - Original Message - From: John Francis [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, November 01, 2003 10:38 PM Subject: Re: Printer resolution (was: Re: posted *istD Samples) With the current generation of printers, it's getting pretty hard to have an image that's higher-resolution than the printer! My current HP is 600 dpi in normal mode, 1200 dpi in best quality. Even on 8.5x11 paper at 600 dpi that's 30+ megapixels - more than a 4000ppi scan can get from a 35mm frame.
Re: Printer resolution (was: Re: posted *istD Samples)
On Sat, 1 Nov 2003 22:38:34 -0500 (EST), John Francis wrote: My current HP is 600 dpi in normal mode, 1200 dpi in best quality. A printer dot (in dpi) is not equal to an image pixel (in ppi). A printer dithers a pixel across many dots to get a good approximation of the color of a pixel. The HP printer is resampling the image to, probably, 300 ppi, then dithering that into a 600 dpi or 1200 dpi pattern. TTYL, DougF KG4LMZ -- Outgoing mail is certified Virus Free by Grisoft's AVG. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.534 / Virus Database: 329 - Release Date: 03-10-31
Re: Printer resolution (was: Re: posted *istD Samples)
On Sat, 1 Nov 2003 22:38:34 -0500 (EST), John Francis wrote: My current HP is 600 dpi in normal mode, 1200 dpi in best quality. A printer dot (in dpi) is not equal to an image pixel (in ppi). A printer dithers a pixel across many dots to get a good approximation of the color of a pixel. The HP printer is resampling the image to, probably, 300 ppi, then dithering that into a 600 dpi or 1200 dpi pattern. Ah, but the HP PhotoPrinters also have multiple levels of intensity; they can deposit different amounts of ink at each possible position. The original PhotoSmart printer was a true 300 ppi printer, without having to dither. The current crop really are 1200 ppi (and in fact they use 1200 x 4800 subpixel dither for even finer level control).
Re: Printer resolution (was: Re: posted *istD Samples)
as i noted in my previous message, the printer driver works at a given maximum resolution that is not the dpi resolution of the printer but a submultiple. in the case of the Epson printer drivers, it is fixed at 360 dpi. anymore more is wasted. the Canon and HP ones probably are 300 dpi, but that is a guess. No - the HP is, as I stated, 600 ppi *input resolution* in normal mode, 1200 ppi in best-quality. You only get any benefit from best quality if you feed it a 1200 ppi image.
Re: Printer resolution (was: Re: posted *istD Samples)
On Sun, 2 Nov 2003 00:13:42 -0500 (EST), John Francis wrote: Ah, but the HP PhotoPrinters also have multiple levels of intensity; they can deposit different amounts of ink at each possible position. The original PhotoSmart printer was a true 300 ppi printer, without having to dither. The current crop really are 1200 ppi (and in fact they use 1200 x 4800 subpixel dither for even finer level control). Then I'll have to take a CD of images over to CompUseless and give them a try. TTYL, DougF KG4LMZ -- Outgoing mail is certified Virus Free by Grisoft's AVG. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.534 / Virus Database: 329 - Release Date: 03-11-01
Re: Printer resolution (was: Re: posted *istD Samples)
Epson printer drivers will not go above 360 dpi. send higher resolution (i.e. 6Kx4K for a 4x6 print) and it will downsample. i suspect Canon ones are the same with a different number, probably 300dpi since their quoted printer resolutions are multiples of 300. Herb... - Original Message - From: Cotty [EMAIL PROTECTED] To: pentax list [EMAIL PROTECTED] Sent: Friday, October 31, 2003 4:33 AM Subject: Printer resolution (was: Re: posted *istD Samples) Off the starting blocks I have always been printing at 300 dpi and always been very happy with the results. I think I tried 200 dpi once and noticed the difference. My image size out of the (light-tight) box is 3072 pixels by 2048 pixels with a file size in Photoshop of 18 MB (from a large/fine jpeg). If I change the resolution to 300 ppi (without changing the dimensions - file size - that is without getting Photoshop to interpolate extra info into the image) then my physical size of print will be 26cm by 17cm or thereabouts. That's roughly 10X 6 1/2. So at 300 ppi, if I want to fill a nice A3 print, I would normally increase the size to (say) 40cmX26cm, also increasing the pixel count from 3072X2048 to 4724X3150, and bumping up the file size from 18 MB to a whopping 42 MB. Photoshop interpolates very well and the prints are really nice. But now if I change things slightly and select a resolution of 240ppi as Mr Evening suggests, the size increase is much less in terms of added Photoshop interpolation. 3072X2048 goes up to 3780X2520, and file size jumps from 18MB to only 26MB.
Re: Printer resolution (was: Re: posted *istD Samples)
In it, the author says that 'the optimum pixel resolution [of the printed image] should ideally be the printer dpi divisible by a whole number. The following pixel resolutions should be used [for a 1440/2880 printer] : 144, 160, 180, 240, 288, 320, 360. The reason for this is fairly simple. The printer driver software uses dithering to get the various shades of colour. The dithering is done for each input pixel, which corresponds to a rectangular array of inkdot sites. For example, a 360ppi image on that 1440/2880 printer has a 4x8 array of possible inkdot sites. If the printer also has two different drop sizes this means the printer can manage something like 64 different levels of each colour at each pixel location. Dithering is much, *much* simpler if the number of input pixels divides the resolution exactly. As most printers embed the dithering in hardware this means that source images at resolutions other than those submultiples will usually be resampled by the printer driver software before being sent on to the device. It's unlikely that the resampling code in the driver will be as good as the image resizing code in your favourite image editing application, and you certainy won't have any control over the amount of extra sharpening (if any) that might need to be applied after this resampling. If you resize the image yourself, though, you retain full control over everything except the final microdrop dithering stage; something the printer manufacturer probably *does* implement as well as they know how. (Incidentally, the quoted example is wrong. While 320 is a factor of 2880, it is not a factor of 1440, and thus is not an optimal resolution).
