Image processing
First of all, I'd like to point out that if you work with image processing, you will have to buy the right equipment deliberately and, unfortunately, without sparing the expense. If the preliminary calculation looks scary, think of the bill for a spoiled job, the loss of prestige and time, and the rotary tiller mentioned in the introduction.
Equipment
When buying a digital camera, the most important considerations are: the lens should preferably not be the size of a match head, it should have optical zoom, a high megapixel resolution should be paired with high light sensitivity (ISO), and it should also be able to save in raw format. Of course, mobile phones, which are being perfected at an astonishing pace, are also increasingly suitable for taking good pictures; we ourselves, for example, take our reference photos with an iPhone6 (and the help of a lightbox).
To digitize existing pictures you need a scanner; here it's worth paying attention to color depth and resolution, but be careful: the latter parameter is often given as an interpolated value, which increases the number of pixels after the fact, so the image becomes blurry when enlarged.
The last big hit to your wallet will be the monitor. The prices of LCD or TFT monitors are tempting even in sizes above 20 inches, but unfortunately their color accuracy is highly questionable. The most important parameter here should be the panel type: while a TN, FILM or TN-Film panel is more than adequate for browsing the web or gaming, accurate calibration is provided by an S-PVA panel. Fortunately, the developments of recent years have reached these devices too, so today IPS displays lead the market in value for money for graphic work (here the weakness of these panels, their slower response time, is not a problem). Of course, if you're happy to buy a used monitor, look for Eizo products - these high-end devices can be had at surprisingly good prices.
Color mode
The images you use should, if possible, all be in the same color mode (this makes it easier to apply a desired change uniformly during printing), and although it is easier to work in the RGB color space during image processing, I recommend only to seasoned, experienced users that they do not convert images intended for the print shop to CMYK color mode in the end, finding out by experience whether any area remained that the latter color space cannot handle. In the settings screenshots you may notice that the embedded color profile is Photoshop 5 Default CMYK. This works well as a general profile, but for demanding users and professionals I recommend not this device-independent profile (and this applies not only to our print shop and our technology), but using the ICC profile that accurately describes the characteristics of the given printer. You can request this from the print shops.
Another common mistake is working in a freshly installed Photoshop with the settings it was installed with. It is the lesser problem if someone works in inches instead of metric units (you could say everyone is free to make their own life harder any way they like), but changing the color profiles is absolutely essential (Edit / Color settings). The default is usually either one of the American settings or Custom, and the CMYK conversion that goes with these is U.S. Web Coated (SWOP) v2. The problem with this is that it gives a calibration tuned to the American practice of negative film imagesetting and to web-press printing on glossy coated paper. I recommend that you download from our site the bundle that makes most of the necessary settings automatically and embeds the Europe ISO Coated Fogra27 color profile recommended for RGB-CMYK conversion.
Resolution
To achieve optimal quality, the resolution of the images should be 300 dpi and the color depth 8 bit at 1:1 scale (that is, the size of the image in centimeters should match the size you want to print). This applies not only to color but also to black-and-white images; let's not forget that our printer has a resolution of 2400 dpi (in the past it was imagesetters that could do this), so the 256 shades of gray can truly be reproduced. For images intended for large-format poster printing, 250 dpi is also acceptable because of the larger size and the resulting greater viewing distance; below that, the loss of quality is already visible. However, if the poster is, say, 70x100 cm and it is a school class photo board, where Mom, Dad, Grandma or any proud relative wants to take a close look at the apple of the family's eye, let's take advantage of inkjet technology, leave the image at the 300 dpi resolution mentioned above, and use a bigger flash drive or compress smartly - I'll write more about that below. If this makes your portrait too rich in detail, don't forget: the curse of adolescence, pimples, can be popped painlessly with Photoshop...
Digital cameras often give us a 115x86 cm image - at 72 dpi resolution, of course. After the correct setting this shrinks to about 21x28 cm, naturally without any change in quality. If your camera supports RAW, set it as the default. It is a strange trap that while people look for cameras with higher and higher resolution, they use the least advantageous option, jpg compression, to save space - and at the maximum level at that.
File format
Before compression, a few words about layers. Of course, it can be very important to keep an editable version of an image for further changes (the program itself warns you about this when saving and suggests making a copy), but for the print shop this is not the optimal format. For one thing, layers, by their very nature, (can) contain text elements that only appear correctly if the font used is available; for another, layers result in a larger file size than necessary, which comes back to bite you: saving, copying to the storage medium, copying it over at the print shop, processing... all take longer. A 300 dpi, A4 image can be as much as 25 MB per layer!
JPG / Valuable color information is also lost with this compression, so I recommend it only in moderation. Be especially careful, because every save after opening the file causes more and more compression, that is, more and more loss of information, so it is really only worth keeping the finished image in this format. What's more, in the age of multi-gigabyte storage devices that fit on a keychain, using maximum compression isn't even justified. Do make sure, however, that the compression method is not progressive but standard (baseline) (the former is a format recommended more for websites, where the image loads quickly but at low resolution and gradually gives way to the higher-resolution version - how many steps this takes is what the scans setting is for).
TIF / This format can also come with compression (LZW), but that is based on a different (so-called lossless) mathematical algorithm which, while leaving the quality of the image untouched, reduces the size with astonishing efficiency in the case of more homogeneous image areas.
PDF / With the right settings, this is the most recommended format (PDF/X). PDF files not only display fonts, page layouts, and vector and bitmap graphics accurately, they also preserve them. Its great advantage is that it compresses color, black-and-white or bitmap images with different mechanisms suited to their nature. Depending on the intended use, you can create a small version meant for on-screen viewing (screen optimized), a true-to-size file that allows good-quality printing (print optimized), or a high-resolution file that can also be used for imagesetting and platemaking (press optimized). Saving from older versions of Photoshop with the Save As command gives no real reduction; in fact, since it even keeps the layers, alpha channels and spot colors, it can result in extra file size. (The record is held by a fine arts college student whose 4-page A4 design weighed in at 978 MB... For comparison: 76 B1 posters, that is, 70x100 cm ones, came to only 920 MB.)
Creating a PDF from Word / Of course, you can create a pdf file not only from graphics programs but also from office programs (Word, Excel, Powerpoint); with their older versions this requires a utility that installs on your computer and can be selected as a virtual printer from the Print menu, and then the pdf file is saved to the location you want. The more adventurous can also choose the more complicated way of printing to a file and then converting it with Adobe Distiller. The newer versions, of course, already include the Save as Adobe PDF function. In the save window you only need to decide on the level of optimization.
TECHNICAL INFORMATION
Download Photoshop color settings
Download Photoshop color profile
Setting up Color Settings:
JPEG settings:
TIFF settings:
PDF settings:
