Understanding Image Size Adjustments in Photoshop

To adjust the size of an image in Photoshop using the method described in the reference, you primarily work with the Image Size dialog, specifically by unchecking the "Resample" option. This method allows you to control the image's physical dimensions and resolution without changing its pixel count.

Photoshop's Image Size dialog (Image > Image Size) is a powerful tool for changing the dimensions and resolution of your images. It allows you to manipulate two main aspects:

• Pixel Dimensions: The total number of pixels wide and high, which determines the image's file size and detail. Changing pixel dimensions is known as resampling.
• Document Size and Resolution: These determine how the image will appear when printed or displayed at a specific size. Document Size is the physical width and height (e.g., inches, centimeters), and Resolution is the number of pixels per unit of physical dimension (e.g., pixels per inch or PPI).

The key to understanding the method described in the reference is the Resample checkbox.

The Role of the "Resample" Checkbox

• When "Resample" is checked: Photoshop can change the pixel dimensions of the image. Upscaling (making the image larger in pixels) involves adding new pixels, which Photoshop interpolates based on existing ones. Downscaling (making it smaller) involves removing pixels.
• When "Resample" is UN-checked: Photoshop keeps the pixel dimensions constant. Changing the Document Size or Resolution will automatically update the other value to maintain the same number of pixels. This method is typically used to prepare an image for print at a specific size and resolution using its existing pixel data.

Adjusting Image Size Without Resampling (Based on Reference)

The method provided in the reference focuses on adjusting the document size and resolution while keeping the original pixel dimensions intact. This is useful for setting print specifications without changing the image's inherent pixel data.

Here are the steps as outlined:

Step-by-Step Guide from the Reference

1. Go to Image > Image Size. This opens the Image Size dialog box, where you can view and modify the image's dimensions and resolution.
2. Un-select Resample to lock the current Height and Width. When you uncheck the "Resample" box, the "Pixel Dimensions" section becomes locked (grayed out). The Document Size and Resolution fields are now linked to the pixel dimensions – changing one will proportionally affect the other, but the total number of pixels remains fixed.
3. Add new values into Resolution and Photoshop will change Document Size. With "Resample" unchecked, increasing the Resolution (PPI) will decrease the potential Document Size (print size), while decreasing the Resolution will increase the potential Document Size, all while using the same number of pixels. For example, a 3000x2400 pixel image at 300 PPI is 10x8 inches. At 150 PPI, it becomes 20x16 inches, using the same 3000x2400 pixels.
4. Finally, amend Document Size under Height and Width, then click Save. After setting the Resolution (or you can adjust the Document Size directly), you can refine the exact print size needed under the "Document Size" section. Photoshop will update the Resolution accordingly if needed, still without changing pixel dimensions. Once you have set the desired Document Size and Resolution based on your original pixel dimensions, click "OK" in the Image Size dialog to apply the changes. You would then typically go to File > Save or File > Save As to save your document.

What This Method Achieves

This specific method, by keeping "Resample" unchecked, allows you to:

• Determine the maximum print size possible at a given resolution with your current pixel count.
• Set a required print resolution for a specific document size, understanding how that fits within your current pixel dimensions.
• Prepare an image for professional printing where exact resolution and physical dimensions are critical.

It's important to note that this is different from typical "upscaling" which usually refers to increasing the image's pixel dimensions through resampling, adding new interpolated pixels to make the image larger for display or printing at a size beyond its original pixel capability. The method described in the reference focuses on adjusting the relationship between pixels and physical size, not increasing the pixel count itself.