Pixel counts for DIgital print quality

[dooda]

I read that a rule for largest good quality digital prints you divide the vertical and horizontal pixel counts by 200. I don't understand what this means exactly. Do you add them together and then divide by 200? Is it 6.1 million divided by 200? I'm not even sure about what the vert and horizontal pixel counts are exactly. Does anyone have any advice here? Can you up the pixel count in photo shop and go by that pixel count or is the quality inherently connected to the sensor pix counts? Thanks for the advice.

[the foto fanatic]

The pixel size of a D70 image is 3008 pixels X 2000 pixels.
Using that "divide by 200" rule of thumb, the resultant maximum print size would be 15 inches by 10 inches.

I can't comment on the accuracy of this rule, though.

[dooda]

Thanks.

So I might do some experimenting here as I'd like to make some prints at 12x18, I'll save the file at 3600 x 2400 or so? Does anyone know what kind of pic quality loss this may amount to?

[Nnnnsic]

Dividing by 200 results in a 200 dpi image, and no, if you up the pixel count in Photoshop while trying to maintain a set dpi, you'll be creating pixels that don't exist and will actually lose quality, or rather, quality integrity.

[the foto fanatic]

Thanks.

So I might do some experimenting here as I'd like to make some prints at 12x18, I'll save the file at 3600 x 2400 or so? Does anyone know what kind of pic quality loss this may amount to?

dooda

The 3002 x 2000 pixel size referred to earlier is a 3:2 format.

If you choose to print 18in x 12in, that is also 3:2 format. You wouldn't need to do any resizing of your image. Your printer should be able to print it as is.

If you use a specialist printing software program like Qimage, you'll have no worries at all. You can get trial version at:

http://www.ddisoftware.com/qimage/

I'd recommend that you try it.

[dooda]

Cricket,

Thanks for the link but I don't have a printer, I was going to take them to a shop and print them there.

What I'm a little nervous about is the different qualities that I'm printing.

Also, if I take the pic in Jpeg, and then save as TIFF, does it make any difference or do I need to shoot in Raw and then save to TIFF to make the quality really excellent?

[Nnnnsic]

Jpeg is a lossy format so you've already lost quality in the image if you go to a tiff with it... but don't worry... you probably won't even notice it.

NEF, as I understand it, is virtually loseless and you can go back to a tiff with no problems... in fact, that's the way to go.

[the foto fanatic]

Cricket,
Also, if I take the pic in Jpeg, and then save as TIFF, does it make any difference or do I need to shoot in Raw and then save to TIFF to make the quality really excellent?

Saving in TIFF is lossless, but the files are large.

If you take your pic as JPEG, then save it as a TIFF file, you won't lose anything from the JPEG. However, this would be pointless as the JPEG format IS lossy, and so you would have already reduced the quality of your image in your camera.

If you take pix as RAW files and convert to TIFF for printing you would have your best quality. I assume from what you have asked that you are unable to have RAW files printed.

I take all my photos in RAW, so that I have the optimum image for any Post-Processing work. However, my print program (Qimage) won't print from RAW files (yet), so I convert to JPEG maximum as the last step prior to printing. I have no problems with the results.

So, to summarise everything I've said - if you take JPEG max files, either straight from your camera, or after conversion from RAW format, to the printer you are unlikely to be really disappointed with the results.
Trevor

[MattC]

I shoot RAW, then save as TIF in NC after any needed adjustments prior to any work in PS. JPEG does not get a look in unless the image is to be emailed or displayed on the web.
I always try to print at 300dpi, but will go as low as 240dpi if needed.
I am still evaluating pxl Smartscale for enlarging. So far, I have had quite acceptable results for print up to 300% with pxl. I had a go at Genuine Fractals, but hated it for its interface and the amount of stuffing around that I had to do.

Cheers

Matt

[dooda]

Thankyou very Much Cricket and Matt.

I printed a copy at 8x12 and I must say it totally sucked. Huge Artefacts in the sky where it goes from light blue to dark blue, plus I over sharpened it somehow. Anyways, I'm back to the drawing board with this. I might have to start looking at shooting in Raw (don't really want to deal with the space issue and time in PP but hey, those are the breaks I guess.