Image quality
Do you have a question about images? Browse the questions below.
What is image optimisation?
When placing your order, you can select the OPT option (automatic image optimisation). This automatically enhances your photos by adjusting colour, brightness and contrast.
At many print labs, optimisation is enabled by default. At Profotonet, it isn’t — we leave that choice to you, as many photographers prefer to fine-tune their images themselves. Have you already edited your photos and calibrated your screen properly? Then we recommend leaving this option turned off.
Tip: Read our article “My print is too dark” for helpful tips on assessing your photos correctly.
When is optimisation applied?
Optimisation is only applied if you select the “Optimisation” option in the filters or settings. When enabled, you’ll see a preview in your design showing approximately how your photo will look with optimisation.How much will my photo change?
This varies per image and can’t be predicted with complete certainty. In most cases, colours are refreshed, brightness is improved and contrast is enhanced — subtle, but noticeable.Which colour profile do you use for photo books?
We print our photo books in sRGB. You don’t need to do anything yourself, we automatically convert all files to the correct colour space.
What is the minimum resolution of a photo in a photo book?
The minimum resolution for an image is 150 ppi. We expose the pages of our photo books at 300 ppi.
Which colour space do you print in?
Profotonet works with its own ICC profiles. When you upload photo files in sRGB, Adobe RGB or ProPhoto RGB, we automatically convert them. In most cases, you don’t need to do anything yourself.
Please note: Submitting files in CMYK (print colours) can lead to unexpected results. We therefore strongly advise against using CMYK.
For professional photographers
Are you a professional photographer and would like to test how our printers handle colour? Read our blog “Does Profotonet offer colour management?”How do I calibrate my monitor?
To accurately judge contrast, brightness and colour, it’s important for photographers to calibrate their monitor regularly.
There are several manual ways to adjust your screen, but the only truly reliable method is using a dedicated calibration device. Combined with specialised software, this creates an accurate colour profile for your monitor. Examples include:
The NIDF has established a standard for digital photography, covering camera settings, profile creation and calibration of your working environment. The NIDF standard can be downloaded from their website.
Is my photo file large enough for the chosen size?
For optimal photo prints, we use 300 pixels per inch (ppi) as a guideline. In the Netherlands, however, we work in centimetres rather than inches. Since 1 inch equals 2.54 cm, this means we use (300 / 2.54) = 118 pixels per centimetre as the reference for an optimal print.
So, 300 pixels per inch is the same as 118 pixels per centimetre.
To calculate whether your photo file is suitable for the chosen print size, divide the number of pixels (either width or height) by the number of centimetres of the print.
Example:
Image size: 3000 × 4500 pixels
Desired print size: 20 × 30 cm
Resolution at this size: 3000 ÷ 20 cm = 150 pixels per centimetre
(Because the image proportions match the print size, you only need to calculate one side.)As mentioned, 118 pixels per centimetre provides optimal photo quality. This image therefore has more than enough pixels for a razor-sharp print at this size. The number of pixels in an image is the key factor in determining whether a photo file is large enough for a specific print size.