From resolution to resampling
As we've previously discussed about Pixel Dimension and raster software, pixels form the structure of an image. The number of pixels indicates the resolution and quality of the file. Although increasing this quality is desirable, it cannot be done arbitrarily and must be done correctly. Unnecessary increases can increase file size and cause many problems during lithography and ripping.
Before reading this article, consider a question that we've touched on in previous articles: When we change the dimensions of a file in Photoshop and our pixel area also changes, how are the added and subtracted pixels simulated? In the following, you will become familiar with the topic of Resampling and see how Photoshop simulates the creation and number of pixels.
It's time to learn how to scale your image correctly. But why is this important? Because if we don't make the right settings when making file modifications, the final result will certainly be heavily damaged. Pay closer attention to resolution and its changes.
Defining Quality
Before doing anything, we must first coordinate with the printing press and lithography to determine what the Print Resolution should be set to. Note that setting the resolution depends on many factors, including the type of printing machine, the type of material, and even the plate. In this example, it is assumed that after consulting with the printing press and based on the Print Resolution topic, the final setting is defined as 300ppi.
Open your file in Adobe Photoshop. From the Image menu, select Image Size and turn off the Resample option. Now enter the resolution number, 300PPI, which the printing press has given you in this section. Although we have changed the image resolution, the Pixel Dimension still remains the same as before, but the dimensions of the file in the Width and Height sections have changed!
As we discussed in articles related to resolution, you will realize how Photoshop has worked; so far, no pixels have been added or subtracted, and interestingly, we have been able to reach the actual dimensions of the document according to the new resolution. Now, if the image is going to be enlarged or reduced, then certainly some pixels must be added or subtracted. Therefore, a pixel simulation must be performed so that Photoshop can maintain quality. Now we come to the Resample option.
It is important to note that the Resample items are not going to perform alchemy and turn a completely low-quality image into a fantastic photo for you. We are supposed to use a suitable image that has a good quality in its normal state and make it slightly larger or smaller in a principled way, not a galactic leap! Because the process of rescaling makes modifications to the pixel structure of the image, and for this reason, it will definitely cause damage. This is where we guide Photoshop by choosing a suitable item to perform the simulation in the best way.
Of course, it is worth mentioning that technology and Photoshop filters, as well as new artificial intelligence capabilities and further advancements, will help us a lot in the future, but at the beginning of the activity, we must provide a suitable process so that we can use these tools correctly.
When you open the Resample menu, you will notice that different methods have been considered for us, which are fully explained on the Adobe website about how they work. That's why we ask you to carefully review this section at this address.
Resample Methods
• Automatic
• Preserve Details (enlargement)
• Preserve Details 2.0
• Bicubic Smoother (enlargement)
• Bicubic Sharper (reduction)
• Bicubic (smooth gradient)
• Nearest Neighbor (hard edge)
• Bilinear
From the small explanation given in parentheses, you can roughly understand which method is suitable for which conversion and how it performs the reconstruction operation. For example, I want to examine a case here: After performing the previous steps about setting the resolution, we want to reduce the dimensions of the file by a small amount. Therefore, we can use the Bicubic Sharper method, which is suitable for reducing the file and specifies how the image should be reconstructed from the beginning.
The Enlargement options are used for enlarging and Reduction for reducing images.
So by understanding the Resample rules, we can correctly scale the graphics files and finally use filters such as Unsharp mask to improve the quality and sharpness of the images. Finally, it should be noted that before changing the dimensions and resolution, check which mode in the Resample section is suitable for your activity. Changing the size very much and very little, not setting the resolution without coordinating with the printing press, or not paying attention to the different options in Resample, greatly reduces the final quality.
And for the future...
- The topic of resolution is related to many factors, and you are not always supposed to send a file in any dimension with a 300PPI resolution for printing. For example, suppose you have designed an architectural sheet in dimensions of 60 × 90 centimeters and are going to print it with a plotter. If we want to calculate the Pixel Dimension of this document, we will face a very large image with dimensions of 70 megapixels.
- First question: What is the capacity of the printer cartridge in the plotter?
- Second question: Can the paper you used tolerate this amount of information?
- Third question: From what distance will the viewer be looking at this design?
It's interesting to know that the human eye, without any special equipment, can naturally perceive around 10 to 12 megapixels. So why would you need to increase the file size so much and damage the paper during printing? Unless, of course, you want a truly high-quality fine art print on premium paper. I'm mentioning this just to prepare you for the next article, because our discussions here are about commercial printing and its principles and rules.
