How to sharpen scanned Tmax 3200 for printing?

[Erik Petersson]

Hello,

I’m about to scan a set of pictures to prepare them for professional printing at a photo service here in Stockholm. The pictures are 35mm b&w. Tmax 3200 so it’s a bit grainy, but that is ok.

My scanner is a Nikon CoolScan 4000 ED, which gives good quality I’m sure. I won’t meddle too much with the photos, just spotting, contrast and curves. However, there are a couple of questions.

- Should I scan at maximum size and downsize as necessary? The prints should be 30x40 cm I think.
- How do I know that the sharpening, which may look fine on the screen, is the best for printing?

Any help would be appreciated. Especially sharpening is a mystery to me. So many theories out there. I’m just looking for robust and easy advice especially as these pictures do not need to be super sharp.

Also, I’ll show you a picture or two to give you an idea of my project. It's from the subway in Moscow, and I wish to print 30 pictures or so:







thanks
/Erik

 

[tkamiya]

I can help you a little.

"Sharpening" really doesn't sharpen anything. It just gives an illusion of sharp image. What really happens is, say there is a transition from light gray to dark gray. When sharpening is applied, at the very edge of light becomes dark, the software makes light a bit lighter and dark becomes a bit darker still. So it kind of creates this bump where change is artificially made larger. It's really hard to explain in words, so you might just look up a term "unsharp mask" and see the graphical representation of what happens.

It is important to understand, the detail that wasn't there in original image won't be there after sharpening. If you over sharpen it, this bump gets larger and it will start to look unnatural. In extreme cases, you can see a rim around this transition area. Here, certainly less is better than too much. On contrasty image, it doesn't require much or any at all. In soft image, you can do a little more but not too much. This is all subjective though.

When I print large, I usually view the image on screen at the size it will print. If it looks ok, I send it. Sure, it won't print exactly the same but you'll have to sort of develop an eye for it yourself. Also, when printing VERY large, I usually do a few test print at 8x10 size before committing to the large size (which will cost money). In your case, you might want to pick ONE image, do a few 8x10, then send it for your final size. Once you know what you get, you can do few at a time, until you get a hang of it.

As to size, I tend to scan at high resolution so I can minimize handling of the film. With my scanner, scanning at any higher than 2400dpi gives me no more detail, so that's usually the max I go. If you can view your image and see grain clearly, it's enough. I don't downsize my image because there's no need other than shorter transmission time to the lab over the net. The printer (software) will size it to whatever it can handle, usually 300dpi for paper.

 

[Erik Petersson]

Hi Tkamyia, thanks for your reply, I will take care to look at the picturer in print size, and I'll do a few test prints before I do the bulk of the copies.

Actually, I think that 8x10 inches is about the size I am aiming for: 30x40 cm. Maybe I was not clear enough...

Thanks also for your advice to scan at high resolution, I was unsure whether that might somehow be worse than scanning at output size. But probably not.

I guess I should get started and make a few test prints. I usually tend to try to get a hang on things through excessive reading before getting started. This works sometimes, but is not always optimal. Then I just get mixed up in all internet advice...

I'll let you know when the exhibition will take place!

thanks again
/E

 

[tkamiya]

Isn't it annoying we can't standardize in measurement, so everyone talk in the same language? I grew up in metric system and had to convert to imperial. I think 30cm x 40cm is little larger than what we call 11x14, which is about twice the size (in area) of 8x10.

I try to research as well and sometimes too much - which gets confusing a lot of the times.

Good luck with your project.

 

[jd callow]

Sharpening does not create detail that is not present, but is does do a few things. First and foremost it helps to mitigate the softening that can occur when scanning and more importantly when printing. An image will not be equally sharp when printed. Printing is never a 1:1 relationship with regard to detail, contrast, density or color balance. All of these items need to be looked at if not addressed prior to printing. Scanning can, and often does, soften an image (it can also create aliasing which gives the appearance of bad sharpening). In these instances you sharpen to maintain what you have. It is not uncommon in my experience that an image that looks a bit too sharp on screen will print perfectly. This is especially true or most apparent with offset printing.

The second reason to sharpen is to create the appearance of detail where the image is no longer large enough to maintain that detail. Many people, myself included, believe that an image's desired output size is not the best size to aim toward when preparing the image. If you need to output an image to a printer that cannot use more than 400spi I have found that if you size an image down to 400spi form something larger opposed to scanning and prepping for the final size the image will give the appearance of having greater detail if when down sizing you carefully sharpen the image in the process.

The final reason for sharpening is for effect, just like you might apply a blur. It is your image if you want the creases and pores of an old man's face to stand out sharpen it.

I sharpen by creating a duplicate layer, apply the high pass filter (radius depends upon resolution) and set the blend for the filtered layer to overlay. By adjusting the transparency you can control the level of sharpness. Additionally you can edit the filtered layer to remove sharpness where it is not needed.

 

[Erik Petersson]

Thanks JD Callow for sharing your experience. I am back at the computer scanning away.

 

[jd callow]

Erik it is often advisable to print a small image and a magnification (at one time referred to a mag) print to test the printer. The small image will let you know if the density and contrast are correct the mag (printed to size but often just a detail so as to save paper and money) will show what detail to expect. You could gang a bunch of small test prints and some mag details (say 15x20 cm each) for relatively low cost. Or at least much cheaper than redoing a bunch of full size prints.

 

[Erik Petersson]

Thanks JD, I wouldn't have thought of that myself.