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Send an RGB file to a printer and what comes back will disappoint you. The colours shift, the bright blues go flat, the vivid oranges turn muddy. This is not a print quality problem — it is a colour mode problem, and it is the single most common cause of unexpected results on flyer, business card, and poster orders in Singapore. Here is exactly what RGB and CMYK are, why the difference matters, and how to convert correctly before you submit.
What RGB is and why screens use it
RGB stands for Red, Green, Blue — the three colours of light. Screens (monitors, phones, tablets) display colour by combining these three light sources at varying intensities. When all three are at full intensity, you see white. When all are at zero, you see black. RGB can produce a very wide range of vivid colours — particularly bright blues, electric greens, and saturated oranges — because it works by adding light.
Design software like Adobe Photoshop, Illustrator, and Canva often defaults to RGB because the end result is typically viewed on screen. If you are designing for digital use only, RGB is correct. For print, it is not.
What CMYK is and why print uses it
CMYK stands for Cyan, Magenta, Yellow, Key (Black) — the four ink colours used in commercial printing. Unlike RGB which adds light, CMYK works by subtracting light: inks are layered on white paper and absorb certain wavelengths, reflecting others back to the eye. The range of colours achievable in CMYK (the “gamut”) is significantly smaller than RGB, which is why some colours look different when printed.
Why the gap causes real problems
Always convert to CMYK before submitting
Bright blues, neon greens, and vivid oranges are the colours most likely to shift when an RGB file is converted to CMYK at the press. If ExpressPrint receives an RGB file, our system will auto-convert it — but the result may not match what you designed. For accurate colour on your flyers, business cards, and posters, always convert to CMYK yourself in your design software before exporting to PDF.
How to convert correctly
In Adobe Illustrator: go to File → Document Colour Mode → CMYK Colour. In Photoshop: Image → Mode → CMYK Colour. In Canva: when downloading, select PDF Print and enable “Colour profile: CMYK” if available — note that Canva’s CMYK support is limited and professional design software is preferred for colour-critical work. After conversion, check your artwork on screen. Colours that looked very bright in RGB will appear slightly less saturated in CMYK preview — this is normal and correct.
For booklets and multi-page documents with photography, convert all placed images to CMYK separately before placing them in your layout. Images converted as part of the overall document conversion sometimes produce less accurate results.
Black in CMYK: one more thing to check
There are two blacks in CMYK: pure black (0C 0M 0Y 100K) and rich black (typically 60C 40M 40Y 100K). Pure black is correct for body text — using rich black on small type causes colour registration issues and blurry text. Rich black is appropriate for large dark background areas. Check that your body text is set to 100K only before submitting any document or brochure file.
ExpressPrint accepts CMYK PDF files
Submit your artwork as a press-quality PDF in CMYK with 3mm bleed and fonts embedded. Our prepress team checks every file before production. If we spot a colour mode issue, we will contact you before printing. Start your order here or contact us directly if you have questions about your file.
Products mentioned in this article:
Flyers & brochuresBusiness cardsPostersBooklet (saddle stitch)Document printing
