The images are probably printing muddy because you are not using a coated paper and the ink is bleeding, which results in excessive dot gain.

If it's being printed litho with a halftone screen then maybe try lowering the screen ruling to an lpi (lines per inch) something closer to what newspapers would use.

http://en.wikipedia.org/wiki/Halftone

You could try printing a CMYK image with a very low screen ruling for a groovy Roy Lichtenstein style effect :)

If the images are full colour (CMYK) you can also try reducing the overall amount of ink that is used to print them by using Gray Component Replacement or Under Colour Removal in Photoshop.

Menu > Edit > Color Settings > Working Spaces CMYK > Custom CMYK...

Under Separation Options - Separation Type select either GCR or UCR and then reduce the Total Ink Limit percentage.

You may want to speak to your printer about the best adjustments to make.

http://en.wikipedia.org/wiki/Grey_component_replacement

http://en.wikipedia.org/wiki/Under_color_removal

I would surmise that, if you are printing on bond paper, you are NOT printing CMYK, but single-color photos, which is another kettle of fish entirely. However, the diagnosis of the problem as dot gain is correct. In order to reproduce the photos better, you will need to flatten the tonal range somewhat, especially in the shadows.

The easiest way to accomplish this in Photoshop is to create a new layer and flood it with white, then set the blending options to Screen. At this point, you will need to generate some test photos to see which percentage of layer opacity yields the best results. Start with a setting of 10%, flatten the image, and save it under a unique name (e.g., test_10pct.tif); undo the flattening,then try 15%, 20% and 25%, saving each one. The example below shows the original phot on the left, and a 10% white overlay on the right. Assemble and label your test photos on a single page in Quark or InDesign, label them with their titles, and have the sample page printed on the same paper you will use for the final product. If you find that one photo is a little too dark and the next step is a little too light, choose an intermediate value, and use it in production. The chosen value may not work optimally in all situations, but the results should be better than doing nothing at all.

Make sure you have the correct color workspace selected (ask your printer - or better yet get a profile from them).

Quarter tones can kill you. You might try dipping them with a Curves adjustment layer.

peace

If this is one-color your darkest black should proabably be around 90%, or maybe even 87% to compensate for dot gain. Use curves in photoshop to do this. You will also need to open up the midtones, (less ink) and probably boost the contrast a bit. Ask your printer for some help on this. They may be able to provide some specific ink levels for you to work with.

Contact the printer. That is the main thing. You need to find out how much ink the paper will hold succesfully and what the dot gain is.

Best of Luck!

peace

Good advice, thanks, I'm going to study the methods proposed and I surely have to ask how much ink can our paper take. We are currently printing at 150 lpi.

What are quarter tones?

This small magazine is being printed CMYK and we want to have vibrant colors and crisp photos because it's a touristic promotion tool.

The reason for switching to bond is to get a warm tactile feeling but also there is a trend to print magazines in bond or uncoated papers and we want to look edgy... you know.

We are considering to use domtar titanium paper instead of bond, this may reduce dot gain and will also mantain the cost of the magazine if we print the cover on the same paper of the interiors, it's a give away magazine anyway.

Héctor

This small magazine is being printed CMYK and we want to have vibrant colors and crisp photos because it’s a touristic promotion tool.

The reason for switching to bond is to get a warm tactile feeling but also there is a trend to print magazines in bond or uncoated papers and we want to look edgy… you know.

These objectives appear to be at cross purposes: best to choose one or the other...

Héctor, I don't think your objectives are completely at "cross purposes". I've seen a few groovy, giveaway, uncoated paper, small format magazines with the look and feel you're aiming for. One of my favourites is Stranger Mag...

http://www.stranger-mag.com/

You can view the mag online, but obviously you don't get the 'feel' of it. With some images they achieve a very nice pencil on paper effect, and the overall feel is much more pleasant than large glossy magazines.

If you keep the Total Ink Limit under 260% and reduce the Screen Ruling (maybe as low as 120lpi) you should be able to print 'cleaner' images with a fuller tonal range. Reducing those values would also speed up drying time on uncoated paper.

However, finding the exact values to get the best results depends upon many things specific to your print job. Paper, ink type, press type, press settings, ambient temperature etc. etc. can all have an effect on the final image quality.

General 'rules' won't always work. The thing to do is build a good relationship with your printer, consider other options they can suggest, keep track of all those variables and adjust them until you get the result you're after.