Updated: Aug 15, 2022
Do you prepare your meals? Yes. Does this make you a chef? No. It doesn't mean that you can't dish up a meal; it just means that you are no Michelin Star Chef.
The same applies to decorating and designing. We can all decorate and meet the basic needs of making a home. Still, sometimes we want to combine colours, texture and lighting and place things together tastefully and then we call on the services of an interior decorator.
On the other hand, an interior designer will consider human behaviour within a space and then design, manipulate, and configure accordingly. It will allow for better effect, movable space, or improved activity within a space and ask for time, careful planning, and precise execution. It brings immense pleasure first to see a client within their new space and experience their appreciation of bringing their vision to life first-hand.
You can create a perfect picture by taking the basic design principles such as balance, repetition, colour, contrast, emphasis, harmony, scale, and details into account. In some cases, less might be more, but this would depend on your style choice and how you incorporate the design principles. There are no wrongs, and senses play a huge role. Is what you see visually appealing? What about that which you cannot see but can experience? The smell or the feeling of space. Do these serve the design purpose?
In the end, it's all a matter of psychology.
In respect of design.