What colour format/space should I use?

Colour reproduction changes from screen to screen therefore the colours in the printed book may differ slightly to your digital photographs. You may also notice differences between different manufactures and medium of print. Please use the RGB or sRGB colour format to ensure that the colours will remain as close to your digital photograph as possible. If your photographs are in the CMYK mode, please convert them to RGB. Bob Books recommends all of your images to be in RGB or sRGB format/space. If your images are in CMYK, please convert them to RGB.

Colour Space

A colour space is a set of colours that can be displayed by an image giving media. Depending on your software settings and the hardware that you are using colour spaces can vary.

The colours used by most digital cameras are adjusted to the sRGB colour space, because this is the colour space that has established itself as the worldwide standard for screen display.

To meet the requirements of as many customers as possible, we base our automatic workflow on sRGB colours that are then converted to the outputting systems with the help of ICC profiles. For digital printing processes we convert the sRGB colours to the CMYK colour space shortly before printing.

All software versions 4.6.1 or newer allow for embedded RGB-ICC Profiles. Images in AdobeRGB, ECI-RGB or ProPhotoRGB colour space will be interpreted correctly in these software versions.

If you send us your images in any other colour space, we are suggesting the following steps to ensure the optimal colour results: Convert your images to sRGB (e.g. in Adobe Photoshop go to “Edit” and then “Convert to Profile”). Afterwards please integrate your images into the layout of your product.

To get the most accurate monitor display possible, we recommend to adjust your settings according to the sRGB standard and to adjust your contrast and brightness according to the test image below.

Colours can vary even if a professional colour management is in place, because differences between the monitor colour space which is a luminous media and the output colour space which is a reflecting media can’t be avoided 100%. Other factors such as the light situation of the environment are also influencing the vision.

Screen Settings

The colour space of your screen is larger than the colour space of printers. The possibility to print exactly what you see on your screen is therefore limited. In addition improper settings and technically inadequate screens can lead to colour deviation.

The ambient light also influences the colour perception. So differences between your screen display and the printed colour is normal to a certain degree.

If you adjust your screen settings as followed you will get the best results:

Colour Temperature: 6500 Kelvin
Gamma: 2,2
Illumination: approx. 120-160 cd/mÇ (also dependent of ambient light).
                                     160cd/mÇ correspond to an illumination level of 500lx.

If you have a measurement device (spectral photometer) and the respective monitor calibration software, you can also follow the instructions in your software. Please open the image from the link above in any photo editing software or your software and maximise the screen. Your monitor allows you to change the settings of the colour temperature, contrast and brightness. Those settings are independent of your computer

 1. Adjust the colour temperature to 6000 – 6500 Kelvin

2. Maximize your contrast

3. Now decrease the brightness until the dark Q (left side of the image) is barely visible.

Also the light Q (right side of the image) should barely be visible.

Automatic Image Correction (AIC)

The AIC optimises the image quality of your photos. It will even out exposition errors and colour issues and it will also adjust the contrast and saturation of the colours for optimal print. The AIC functionality is fully automatic. The intensity of the adjustments is determined by an image analysis. The settings are optimised for the majority of all images. So on average the AIC will improve the image quality. We recommend turning it on by default.

Only sometimes it is better not to use the AIC. For example if you already optimised your images with a photo editing software and you don’t want to change the results any further. In these cases you can either turn the AIC off for single photos or for your whole project. Please go to “Options” and “Photos” in your Software to adjust the AIC settings.

Sharpening

We always sharpen images slightly. This is independent on the AIC being turned on or off. We recommend to not sharpen images significantly in an external software.

Red-Eye-Correction

Red eyes can occur in images if flash was used in a dark environment. The light flashes through the widely opened pupil onto the retina, i.e. the red inner part of the eye.

You can change the red-eye-correction settings under "Options/Photos" as followed:

•  Ask for each photo

•  Always reduce red eyes automatically

•  Do not automatically reduce red eyes

If the red eye correction is turned on, you can see the effects directly in the editor.

Resolution

The resolution of your photos should be based on 300 ppi (pixel per inch) in relation to the printing size in your layout. If your photos have a resolution of more than 300 ppi in relation to the printing size, the software will automatically downsize to 300 ppi.

If you change the size of your image in the layout, or if you only use an image section or if you zoom, the resolution will be adjusted accordingly. 

An important tool to check the resolution of your images based on their size is the smiley in your software. It can be found in the top menu bar and can be red, yellow or green. If you click on the image and the smiley is green, the resolution is high enough to ensure that you are not decreasing the quality when your product is printed or exposed. This is still the case if the resolution is less than 300ppi in relation to print size. The threshold varies depending on printing method and printing material. If the smiley is yellow, the resolution is still ok, but not optimal. If the smiley is red, we are strongly recommending to downsize your image, so that the resolution increases and the image quality will reach the yellow or green standard.

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