Thread: Optimize photos for poster printing

Optimize photos for poster printing Your home inkjet photo printer prints photos in a maximum size of A4, but you need more impressive posters. Unfortunately, a professional A3 printer is far too expensive.

Numerous photo material suppliers, for instance, Digital Photo Printing, Free Online Photo Albums & Digital Photo Sharing - Snapfish:. specialize in large format prints. However, the rules that apply to large-format poster prints are different than those for small¬format prints. You need to adjust and color correct your photos for anything close to the best possible results.

You can, of course, simply upload the unedited photos and trust the website to automatically optimize them well. That might work, but not all the time. It would be better to prepare the photo beforehand, exactly the way you want it and ask the respective photo printer not to undertake any further photo optimization after uploading the picture to the website. The following steps are 'particularly important while editing a photo on your own.

CORRECTING COLORS

Almost all suppliers support the sRGB color scheme. Therefore you should use this even while editing your photos. In Photos hop, you can set the color scheme under 'Edit I Color settings'. This will make the colors in the print consistent with those in the image you see on your monitor at home.

SETTING THE RESOLUTION

For poster printing in the 50 x 75 em format for instance, which is the largest size offered by many suppliers, the image file should have a minimum resolution of 300 ppi (pixels per inch). A higher resolution is not required. If a poster printer displays at resolutions like 1,440 dpi (dots per inch), it unfortunately affects the print resolution, which multiplies due to the raster. You can ascertain how many dpi a picture of a particular size contains, with t~e 'Image. Image size' function in Photoshop, Simply remove the check mark in front of 'Recalculate image' and type the desired size or resolution

Incidentally, photographic subjects also make do with low resolutions. From a viewing distance of about a mer-Sr, you can hardly make out any loss in sharpness even at 200 dpi. For particularly large format posters, even 100 or 150 ppi is sufficient in some cases, from a distance of more than one meter. However, edges of fonts or graphics appear considerably smoother at a 300 dpi resolution.

RETOUCHING PHOTO ERRORS

Scrutinize your picture carefully and touch up all minor details. In the large format, these very minor details will quickly become huge unsightly elements, which are strongly noticeable and can severely affect the overall impression of the subject. Pimples or color fringes can destroy a portrait. Moreover, check the histogram. Lifeless pictures without 'crispness', which means without powerful contrasts, make really un-sharp, slack posters.

SETTING THE SHARPNESS

Before uploading the picture to the supplier's website, edit it using the 'Unsharp mask' filter, which can be found in Photoshop under 'Filter Sharpen'. The intensity depends on the subject, the size of the print, the printing process as well as the paper used. You
can basically use a considerably higher sharpness for the large print as compared to smaller prints and more sharpness for matte paper than gloss. Always check the sharpness at a 100 percent view. Only then will you get an impression of the real effect of the selected settings.