西洋画的基本知识
Basic knowledge of Western painting

西洋画的门类虽然很多，但是不论那一种绘画都是出发于自然模仿的再现，而进于合理化的科学方法，由这种科学的合理方法就产生出西洋画的基础知识来，这是研究西洋画者所应最先明了的。

透视

什么叫做透视法呢？就是透过假设的透明平面，以观察景物，依照透明平面上的景物形象来绘画的方法。这绘画上所根据的远小近大的法则就是透视法，也叫做远近法。

我们要知道物体的实际形状与我们视觉上所看到的，可能并不一样，那我们就要根据所看到的形状而描画在画面的平面上。譬如一本书，我们都知道它是两边相等的长方形，它的两组线是平行的，假使你按照自己所知道的书的实际形状而画出来，那么你就错了，因为视觉上的那本书已经不是长方形，而是梯形或菱形的了，而这就是我们要画的透视的形状。

绘画在平面上是表现立体感觉的，画面上的空间要符合一定的透视原理，否则你画的空间就会使人感到不自然的了。那么透视法则的所谓“远大近小”这变化过程是怎样的呢！让我们在下图说明。

The various genres of Western painting all originate from the imitation of nature and progress towards a rationalized scientific method. From this scientific and rational approach arises the basic knowledge of Western painting, which is the first thing that researchers of Western painting should understand.

Perspective

What is perspective? It is a method of drawing by observing objects through an assumed transparent plane and depicting them according to the images on that transparent plane. The principle of drawing objects smaller in the distance and larger in the foreground is called perspective, also known as linear perspective.

We need to understand that the actual shape of an object may not be the same as what we see visually. Therefore, we must draw based on the shapes we see. For example, consider a book. We know it is a rectangle with equal sides, and its lines are parallel. However, if you draw it based on your knowledge of its actual shape, you would be mistaken because visually, the book is no longer a rectangle but a trapezoid or rhombus. This is the perspective shape we need to draw.

Painting on a flat surface is about conveying a sense of three-dimensionality. The spatial arrangement on the canvas must adhere to certain principles of perspective; otherwise, the spatial representation in your painting will appear unnatural. So, what is the process of the "distant objects appearing smaller and closer objects appearing larger"? Let's illustrate it in the diagram below.