Hi,
I've done a fair amount of testing (and used a lot of paper!!), so I thought I would report back with my conclusions.
PRINT RESOLUTIONFirst of all, I checked out the effect of print resolution, from the link that Bart gave me:
http://www.luminous-landscape.com/forum/index.php?topic=54798.msg447163#msg447163.
I did the testing on my HPZ3100, which has the following print options:
Render: 300ppi Print 1200x1200
Render: 600ppi Print 1200x1200
Render: 600ppi Print 2400x1200
I printed on a high gloss paper after having calibrated the printer/paper and profiled the paper using i1Profiler and an i1Pro2.
DITHERING SMOOTH COLORS (I checked 3 different shades).
First of all I eliminated the 2400x1200 print resolution (the printer does extra passes to achieve this) as the dithering was LESS smooth than at 1200x1200. I could see this by scanning the print at 4800dpi. There may be some advantage for diagonal lines, for example, but I see no advantage for photography.
The smoothest dithering was on the 600ppi 1200x1200 (when viewed using a 4800dpi scan). However there is no visible difference to the eye between this and the print at 300ppi 1200x1200. There
may be a
barely noticeable difference using an 8x loupe. So, from a tone/color point of view there seems to be no discernible advantage in going to 600ppi. BTW: the printer matches the 300ppi dithering when printing at 600ppi by doubling the number of passes; the spot sizes are identical: so my conclusions here may not be valid for an Epson as the Epson print head is capable of changing the spot size.
DOWNSIZED PRINT
With the print downsized for 300ppi but at print resolution for 600ppi, there is no visible difference between the prints (by eye or with an 8x loupe).
UPSIZED PRINT
With the print at print resolution for 300ppi (but upsized x2 for 600ppi), there is no visible difference between the prints (by eye or with an 8x loupe).
With the print upsized by 2x for 300ppi (and 4x for 600ppi), the 300ppi print is better, as expected (although the difference is surprisingly small).
All of the resizing was done using Photoshop with resampling set to Automatic. I used Nik Sharpener 3 for the final output sharpening, after resize, same amount in all cases (the only other sharpening was a small amount of raw sharpening in Lightroom).
CONCLUSION
My conclusion is that there is no advantage (with the Z3100 at any rate) in printing at 600ppi. IMO, the best setting is 300ppi for the print, 300ppi rendering resolution in the print driver and 1200x1200dpi printing. My view is that upsizing to 600ppi will only damaging the image. However, if the image resolution is at 600ppi or higher (in other words, a very small print – about 24x16cm for a 1DS3 21MP image), then there may be a very slight advantage in printing at that resolution.
I haven’t tested on matte paper, but I expect the same results – but with less sharpness overall because of the ink diffusion on the matte paper.
QIMAGE v. PHOTOSHOP/LIGHTROOMAs far a printing goes, there is no difference between QImage and Photoshop (I haven’t tested against Lightroom as I expect that LR and PS will be the same or very similar). It comes down to sharpening and resizing, and there is quite a difference there, as one would expect.
SHARPENING
I’m new to QImage (having just purchased it) so I may not be using it optimally. The test was a 3x upsized image printed at 300ppi on both Photoshop and QImage.
QIMAGE DFS
At first sight, the QImage Deep Focus Sharpening appears to be really excellent. It sharpens the image with no visible haloes.
However, what it does is to lighten and darken pixels, not just at the edges, but over a much wider area, so that it’s a bit like adding local contrast. This certainly gives the impression of sharpness, but at the expense of tonal change in the image and desaturation of the lighter colors. For example a light colored leaf or reed may easily become leached to white or to a much paler color.
On the other hand, what is good is that the DFS appears to be applied AFTER resizing. If used carefully it gives a good result.
SHARPENING AND UPSIZING
I made 3 comparisons:
1. Upsize and DFS sharpen in QImage (effectively one operation)
2. Upsize in Photoshop; Smart Sharpen; Output Sharpen using Nik Sharpener Pro 3
3. Upsize in Photoshop; Smart Sharpen; Output Sharpen + Local Contrast using Nik Sharpener Pro 3
With 2 and 3 I used a raw smart object with the Smart Sharpen filter below the Nik Sharpener filter (so that the Smart Sharpen is applied first).
1 appeared sharper than 2. On close examination I could see that this was due to the increased local contrast in the QImage print, so I added a small amount of Local Contrast in the Nik Sharpener filter (the filter can apply Output Sharpening, Structure, Local Contrast and Focus at the same time) and reprinted the image as 3. At this stage QImage and Photoshop prints appeared equally sharp.
There is really nothing to separate the two prints 1 and 3 viewed at normal distances. However it is clear that the QImage print, 1, has a loss of detail as you can see in the scanned image below. There’s a sort of posterization effect, so that the rock, for example, appears to have gray patches where there should be a variation in tone, resulting in a loss of structure to the surface. Also, there is a leaching of color in the reeds for example (not visible in the scanned image below).
CONCLUSION
My conclusion is that QImage does a superb job and does so almost automatically. I do think that it is possible to achieve a better result in Photoshop, and certainly a much more controllable one: so I will continue to use Photoshop for critical prints, but I do intend to use QImage where ‘pretty good’ is good enough.
Nik Sharpener Pro 3 (which I had but wasn’t using) really does a very good job of output sharpening, local contrast and ‘structure’ and it has a
great feature in that the image can be soft-proofed to show how it should look on print (from a sharpening point of view). This soft-proofing (sharpening) feature would be a fantastic addition to QImage. However I prefer Photoshop Smart Sharpen for normal sharpening to the Nik Focus sharpen: Smart Sharpen is very controllable and it’s easy to cut out haloes, damp down shadow noise etc. The Nik Focus sharpen has no controls except for Strength.
You can see a larger version of this image here:
http://www.irelandupclose.com/customer/LL/QUvPS.jpgI hope this has been of interest and with any luck we’ll have an interesting discussion to follow!
Robert