Previewing for Printing

[Thlayle]

When I am producing a photo for print purposes, I try to peek in very close to see if there are bothersome artifacts, anything from noise, chromatic aberration and just other odd-looking effects (yes, that's about how advanced I am at this).

My question is this: how close do you look? I can always find something if I drill in close enough. I realize this has to be related to the size of the print I am considering. Still, if --for example--I am not seeing much that is bothersome at 200% zoom, is that going to be good enough? I feel as though hard proofing is the only real way for me to be satisfied. Still, I'd like to be sure I am at least in the ballpark before any kind of printing.

Hope this makes sense. It's not a question of how to treat the details and remove things, but how do I "see" it closely enough before hitting the "print" button. (Btw, on that count, all my prints go to lab, not my own printer.)

[xpatUSA]

When I am producing a photo for print purposes, I try to peek in very close to see if there are bothersome artifacts, anything from noise, chromatic aberration and just other odd-looking effects (yes, that's about how advanced I am at this).

My question is this: how close do you look? I can always find something if I drill in close enough. I realize this has to be related to the size of the print I am considering. Still, if --for example--I am not seeing much that is bothersome at 200% zoom, is that going to be good enough? I feel as though hard proofing is the only real way for me to be satisfied. Still, I'd like to be sure I am at least in the ballpark before any kind of printing.

Hope this makes sense. It's not a question of how to treat the details and remove things, but how do I "see" it closely enough before hitting the "print" button. (BTW, on that count, all my prints go to a lab, not my own printer.)

On another site, I get slapped around a lot for zooming in to see such stuff. My latest post there about Sigma camera aliasing involved zooming in to 1000% [sic] with no smoothing. All that even though I view whole images fit to screen on a 2K monitor and don't print.

https://www.dpreview.com/forums/post/63101890

For your purpose, I would base your zoom level on a) how big your print is and b) what viewing distance you use for that size print. We could help more if you told us those.

Another way might be to think in terms of human visual acutance - the Snellen Chart thing. There would little in zooming in to detail that the eye could not see in the print, for example:

A 5x7" card printed at 720ppi compared to the same card printed at 180ppi ... I image that the needed hard-proofing zoom level would differ betwixt the two ...

[Shadowman]

Sometimes you have to zoom in and sometimes you have to zoom in even further to make the corrections, so do whatever pleases you.

[Manfred M]

Let me suggest that 100% of captured size is probably the optimal size to review any image. That way you know there is NO interpolation of the image by the software and what you see is essentially what is actually there. If you can't see it at 100%, they you are wasting your time in refining that aspect of the image by zooming in closer.

Prior to printing I will resize the image to final print dimensions (upsampling or downsampling, depending on the final image dimensions) and set the image ppi to the printer's native dpi and apply output sharpening at 100% of that file size in the final print image format . Any artifacts from the output sharpening stage can be seen this way. If the image starts showing artifacts like halos, cut back the amount of sharpening. Do this at 100% again.

As you are using a commercial printer, chances are that they are using a chromogenic printer that has a native resolution of 300 dpi and uses 8-bit JPEG in the sRGB colour space as image format. Most commercial photo printers use this; chromogenic, digital press and HP and Canon inkjet printers. The only exception are Epson inkjet printers that run at 360 dpi. Ink jet printers are the only ones that can support wider colour spaces, but many print shops have standardized to sRGB 8-bit JPEGs for these printers as well, but it is worth checking to see if they support Adobe RGB or wider colour spaces.

I always do test prints (often several of them). Smaller than full size and my final test print will be a part of the print at 100% size.

[Manfred M]

A 5x7" card printed at 720ppi compared to the same card printed at 180ppi ... I image that the needed hard-proofing zoom level would differ betwixt the two ...

Ted - printers have fixed resolution print heads with most running at 300 dpi (chromogenic, digital press and HP and Canon inkjet photo printers). Epson ink jet printers run at 360 dpi. I understand that large format printers used for outdoor signage applications and canvas prints are run at 150 dpi.

If you look at the actual print head design on ink jet printers an 8 cartridge printer will deposit ink from zero up to all 8 cartridges so a "dot" of colour contains up to 8 smaller "dots" which is why inkjet manufacturers will sometimes refer to them as 2400/300 dpi.

"Best practice" is to prepare the output version of the image (in ppi) to be value as the printer dpi. This means that the scaling only occurs on the computer and bypasses the scaling engine in the printer itself.

[Thlayle]

Thanks for your comments, Ted and Manfred. The project I was working on that brought up my question is an 18 x 24 print of a landscape setting. I started from a full raw file (essentially no cropping) which is the 2x3 ratio from my Canon T2i. So it seems I have plenty of pixel depth to work with.

Manfred, I have seen some of your comments before on the resizing steps prior to printing and have adopted those. I will probably always find myself zooming in extremely close for some checking of my work, but it is good to hear that 100% should work well.

As much as I love photography, even the post-processing that comes with digital work with raw files, preparing for quality prints is a big challenge on its own for me.

Again, thanks.

[DanK]

Randy,

At the risk of seeming too casual about my printing, I'm going to suggest that you may not have to make this so difficult.

First, I print from Lightroom rather than Photoshop. That may be enough for you to discount the rest of what I write. However, I have found that Lightroom's resizing and output sharpening algorithms work well, and the Lightroom print module has a lot of very convenient features--in particular, user-defined templates. You can set whatever you want and store it as a template. For example, I print more on Canson Baryta Photographique than any other paper. I have several templates set up for this. I have two for 13x19 prints, one with room for a signature and one without. When I select one of those templates, most of the key settings, including printer settings, are set with that single mouse click. I have never had anyone make a negative comment about the quality of one of my prints. (Of course, I get plenty of negative comments about images that I choose to print.)

However, that's not why I'm posting. I just mention Lightroom in case you see that as a reason to discount some of what follows.

First, I agree with Manfred: if you are inspecting for possible printing problems, there is no reason to go above 100%.

Second, there is only one circumstance in which I inspect an entire image at a high resolution, section by section: when I have used focus stacking. Focus stacking can create halos, and if they are small or faint enough, one may not notice all them on screen without enlarging. I don't need 100% for this and usually use less, often 50%.

Instead, I spot check as I am editing, in part to check focus and sharpening. It's usually clear where problematic areas are likely to be. For example, I just posted two bug macros. I always check the eyes of these images at 100%. I do the same with the eyes of people in candid shots. If you are shooting high-contrast edges, e.g., branches against a bright sky, those edges would be a good place to check for chromatic aberration, although I don't think you would need 100%. And so on.

Smaller sizes hide lots of problems, so the larger I am going to print, the more I worry about these details.

Manfred's comment about test prints is an important one. There are several reasons to do test prints. I often use them to check the colors of output, and for that, you may be better off doing small prints of the whole image, to have the full range of colors. But Manfred's suggestion of printing portions would be better suited to checking for the sorts of artifacts you are worried about. To be frank, I haven't been doing that and don't think I needed to for the images I have printed recently, but I can see cases where that would be the way to go. For example, I rarely print my bugs more than 8 x 10 because most people don't want huge bug images hanging on their walls, but if I were printing them large, say 13 x 19 or 17 x 22, it would be best to do a test print of the eyes at the size they will be printed.

Dan

[Manfred M]

Dan has alluded to why I do a final check on my work at 100% at the end just before I print and that is effectively a "final quality check" on the image.

There are times in my workflow where I do a check at 100%; removing sensor dust from areas where it can be noticed, validating local sharpening or checking boundaries where I have been dodging and / or burning, etc. I will zoom in to greater than 100% when working on very fine adjustments but my reason for doing so has nothing to do with wanting to pixel peep, but rather it is just easier to make reasonable length motions with my Wacom tablet or mouse, depending on which tool I am using at the time.

What I have written about is really my "final check" where I am looking for post-processing artifacts. A well retouched image is one where the viewer cannot see any "breadcrumbs", i.e. signs / artifacts from the retouching work.

Just to add one more comment on printing from Photoshop vs Lightroom and my personal workflow. I agree that the Lightroom print interface is simpler than the Photoshop one. I do virtually 100% of my printing from Photoshop for one simple reason. My output sharpening technique requires layers. I don't output sharpen certain areas of any image that I print, so I use a layer masks during this operation. I don't sharpen extreme highlights or extreme shadow areas (these don't look right when sharpened. I will not generally sharpen the sky or water or skin that I have softened in post. I sharpen high frequency areas (leaves and grass) less than I output sharpen other parts of the image. Can I see the difference between an image I've worked this way and one that I haven't? The answer is yes and the larger the print size, the more obvious it is. If it didn't make any difference I wouldn't take the time and effort to do so. I'm looking at A3, A2 (13" x 19" or 17" x 22") or larger. A4 / 8-1/2" x 11" and smaller I don't go into this level of sharpening but a reduced subset of it because I can't see the difference.

[DanK]

Manfred,

Interesting. When you do output sharpening in Photoshop, which sharpening method do you use, or does it depend on the image?

In "creative sharpening" (you probably recall that I don't actually buy this term), I use three methods: deconvolution, USM, and high-pass. My understanding is that Photoshop's "smart sharpen," when it is set to "lens blur", is deconvolution, and LR's sharpening transitions from USM-like to deconvolution as the "detail" slider is moved to higher values. I'm finding that I am using the old-fashioned high-pass approach more and more because it can ignore smooth areas. I have no clue what method Lightroom uses for output sharpening or whether there is any masking involved, but I think I'll see if I can find information on that.

Dan

[Donald]

100%. That's as much as is required to pick up any artifacts ahead of printing.

[Manfred M]

Manfred,

Interesting. When you do output sharpening in Photoshop, which sharpening method do you use, or does it depend on the image?

In "creative sharpening" (you probably recall that I don't actually buy this term), I use three methods: deconvolution, USM, and high-pass. My understanding is that Photoshop's "smart sharpen," when it is set to "lens blur", is deconvolution, and LR's sharpening transitions from USM-like to deconvolution as the "detail" slider is moved to higher values. I'm finding that I am using the old-fashioned high-pass approach more and more because it can ignore smooth areas. I have no clue what method Lightroom uses for output sharpening or whether there is any masking involved, but I think I'll see if I can find information on that.

Dan

For in-process sharpening

I use USM pretty well exclusively and generally only vary the amount and radius and typically leave the threshold at 0 for this type of fine work. I make a copy of the image layer, set the opacity to 80% (that gives me a bit of headroom should I want to increase the effect globally) and sharpen. I sharpen for the area that I want the largest amount of sharpen applied to. When I do a portrait, that is usually the iris. I then apply a black layer mask to hide the sharpening.

I will use a soft brush and set my flow rate to somewhere between 10% and 25%, set my brush to white and start painting the areas I want to do an in-process sharpen to. Iris, lips, eye lashes and eyebrows are generally what I work at, although somethings I will also sharpen parts of the jewellery like stone in earrings. I zoom right in and apply the sharpening to individual hairs in the eyelashes and eyebrows and build up the sharpness. Once I understand how much buildup I want in an area I will adjust the flow so that I can down the sharpening with one or two brush strokes. I zoom in and out to 100% to assess how everything is looking. In the end, I try to adjust to overall opacity of the adjustment layer so that the finest details look right at 100% zoom and might tone down the sharpening on areas like lips and irises, as needed. As a final step I tweak the opacity of the sharpening layer, again at 100% to fine tune how it looks.

I've used this method so long that doing this probably takes me about 5 minutes to do this precise sharpening. I generally crop out the areas that I haven't sharpened. That reduces the overall file size a bit.

I use a similar method when doing in-process sharpening in landscapes (leaves or grass and tree bark) but find I can get away with less accuracy and faster brushstrokes.

I tend to use a very simple workflow in my sharpening and dodging and burning using fairly simple tools. I find that this works for me.

Output Sharpening

I use the same basic approach for output sharpening but with a few exceptions.

I flatten the image I am working on and save it as a new working file.

If I want to use a different colour space than the one I am working on to print, I do that conversion next. This generally only occurs when I am editing in L* a* b*. I resize the image to the final print dimensions and change the resolution so that the ppi matches the native resolution of my printer (360 ppi for my Epson P800). This is also the point where I would drop to 8-bit, especially if I am using a 3rd party printer (they don't tend to want 16-bit images). When I print my own, I just leave things alone. A high quality photo printer doesn't resolve to even 1 million different shades,so 16-bit is not required for printing.

I duplicate my image layer and go to 100% resolution and opacity to 80% and sharpen to get the subject / area of interest to look right. Again I use the USM and tend to sharpen to at least 100% (sometimes much higher), radius around 1 and threshold is usually 0 - 4.

The next thing I do is apply the BlendIf on "This Layer" using the default gray setting and move the black triangle to around 20 <Alt> click on it to split it and move the right to a value of around 40. I go to the right hand side of the BlendIf and set the white triangle to around 240, <Alt> click to split it and move the left triangle to around 220. If you haven't used it before it is found under the Layer menu on the Layer Style dropdown where you pick "Blending Options" on the dropdown box that pops up. You can also double click in the gray area to the right of the image in the layer palette to get there. What this does is that it applies the output sharpening variably. On the black, no sharpening is applied to values that are 20 or less and feathers the values from 20 - 40. On the lights, no sharpening is applied to values from 240 - 255 and it is feathered from 220 - 240. What this does visually is it does not sharpen areas of extreme dark shadow detail or extremely light highlights. These areas look strange when sharpened, so I don't sharpen them.

My next step is to paint out any other areas I don't want sharpened as much; skies, water, fine leaves, grass, gravel, sand, etc,, i.e. high frequency areas. I either use a selection tool or just use a soft brush (25% flow) to reduce the sharpening impact in those parts of the image.

At this point I am ready to print out of Photoshop. I will generally view the image at 100% and might change the opacity of the sharpening layer. I will boost it a touch when printing on uncoated papers and might drop it a bit for coated luster or higher gloss papers. Experience with the specific paper is my guide here.

I generally throw out my print file when done printing. All this work generally takes less than 5 minutes and is dependent on the print size. I generally only do a single print and the steps don't take a lot of time to redo if I were to want to reprint at the same size at a later date.

[DanK]

Manfred,

Thanks for taking the time to write such a detailed explanation. I've bookmarked it and will try these approaches down the road.,

Dan