Adobe Photoshop is one of the most popular packages for processing bitmap graphics. Despite the high price, up to 80% of professional designers, photographers, and computer graphics artists use the program. Due to its enormous functionality and ease of use, Adobe Photoshop has a dominant position in the graphics editor market.
About Adobe Photoshop.
Topic 1.2. How do I resize a photo in Adobe Photoshop?
Resizing a picture in Photoshop is a simple matter at first glance. But for an inexperienced user it often causes difficulties. Output frame quality is not always what we expected.
The reason is simple - you need to figure out what the bitmap size really is. To do this, you have to read a couple of paragraphs of theory.
Some theory
Almost any course of lectures or tutorial on Adobe Photoshop contains the phrase "raster (pixel / dot) graphics". What is it?
Raster Graphics is a matrix, each cell of which is a colored dot. This is a "natural" aspect ratio. All living beings see "points". And already our brain combines them into lines, contours, images. Printing and displaying on the screen are also built according to the laws of raster graphics.
What is a pixel? Pixel is the smallest unit of information in raster graphics. When printing it is a drop of ink, when chasing it is a point of impact, on the monitor it is a luminous cell. They can be called a point or a pixel. However, the pixel has no fixed size.
Now let's talk about size and quality. The physical size of a bitmap is measured in pixels. The more of them, the better the picture is. Example: Try to draw a path not with lines, but with points. Agree, the more often they are placed, the smaller their size - the smoother and sharper the lines seem.
A pixel can be very large and extremely small. For example, a drawing on a balloon. When the ball is without air, the image on it seems extremely dense, smooth. If we inflate it, we will see how the picture breaks up into separate "points". It doesn't look so good anymore. This is a visual demonstration of the ratio of quality and size of the printed impression (RPO). The amount of paint on the ball is constant. By inflating it, we do not improve the image quality. We are just stretching the image over a large area. And at a certain stage, our brain ceases to perceive the points as parts of the picture, but sees them separately.
We have come to the concept of " Image resolution ". Bitmap resolution is the number of dots to fit in the unit. Traditionally, resolution is called pixels per inch. The larger it is, the better the print or projection will look.
Practical part. Resize the photo.
Access to photo resizing functions is located in the corresponding block of the “ Image ” menu. The item " Image size " is responsible for resizing the image itself and the printed sheet. The item " Canvas size " - for the size of the form on which our image is placed.
Open any image. In our case, a photograph of a horse.
To resize the photo, select Image Size from the Image menu.
The dialog box that appears has three blocks:
1. The first, " Dimension ", is responsible for the dimensions of the photo in pixels. The top line is the approximate size in megabytes (uncompressed).
Changing the dimension parameters will physically increase or decrease the picture. In the drop-down lists of measurement units, you can select only two positions "pixels" and "percent". The latter is the percentage of the current size.
2. The second block is the size of the printed sheet. He is responsible for the print size and resolution (dots per inch). There are many more measurement options. Sheet size can be measured in almost anything, down to "typographic points".
Figure 1: Image Size Window Blocks
3. The third block allows you to select the types of changes.
The first - " Scale Styles " indicates the need to increase / decrease the size of the effects superimposed on the photo.
" Maintain aspect ratio " - will preserve the aspect ratio of the photo. When changing the height parameters, the width is automatically changed. Canceling this item allows you to change the geometry of the picture.
And finally, " Interpolation ". This item is responsible for resizing the print while maintaining the dimensions of the picture in pixels. To use the example above, this is inflation or deflation of a balloon.
To resize a photo in Photoshop:
- Open the Image Size dialog box.
- Set the required parameters (number of pixels, size of the printed sheet).
- Click OK or Enter .
Practice Notes:
- When Interpolate is selected, resizing the image automatically resizes the print. And vice versa. If you want to change the dimensions of the print, the resolution without changing the physical dimensions of the frame (number of pixels), uncheck this item.
- An increase in the number of pixels does not always lead to an improvement in the quality of the picture (there is nowhere to get information into new pixels - the “search for average” algorithm works). But it always leads to an increase in the file size on disk.
- It has been experimentally proven that from a distance of 1 meter, a person with normal vision does not see individual pixels at a resolution of 72 dpi (dots per inch) and more. All monitors operate at approximately this resolution. This is also the basis for the use of graphics in Web design. There is no need to post unnecessarily "heavy" photos: the user will not see more pixels anyway.
- For printing and printing, alas, high permissions are required. For printing newspapers, leaflets, etc. it is worth setting at least 300 dpi. Some media (especially glossy magazines) work with 1200 dpi and higher quality photos.
Canvas resize
This item is used to resize graphics. The key feature of the tool is that the dimensions of your frame remain unchanged: a solid-color field is simply "drawn" around it. Canvas resizing is very common when creating collages. When you need to add some more fragments to the base image.
To resize the canvas:
- Select the appropriate item from the Image menu
- Set the required canvas dimensions. Please note: setting the size smaller than the current size will automatically crop your frame.
- Clicking on the arrows in the " Location " block, edit the position of the frame relative to the fields being drawn.
- From the Canvas Expansion Color menu select the desired color.
- Click OK or Enter .
The Topic of Article: Photoshop tutorials. Topic 1.2. How do I resize a photo in Adobe Photoshop?.
Author: Jake Pinkman | 
