In the first instance, your camera should be set to capture the largest image size possible. RAW files will always result in the largest images and will always give the best results.
When you edit a RAW file, whether it be in Lightroom or any other editor, you will be editing it at its full size. When you edit any file in Photoshop, it makes sense to edit at its maximum size also as this maintains the highest quality level possible.
While the largest image sizes are great for editing purposes and for printing, they’re less than ideal for uploading to social media or anywhere your images will be displayed on a screen. So, it makes sense to resize – ie DOWNsize – your images for screen display. This results in smaller file sizes which means your image will load more quickly. If you intend to print your image, then don’t resize!
When resizing, there are two things to consider:
- pixel size: this is the physical size of your image measured in pixels.
- resolution: this refers to the number of dots (or pixels) per inch. It is usually referred to as dpi or ppi.
When you are viewing your image on screen, it is the pixel dimensions of your image which determine how big it appears. So, if you are viewing an image with pixel dimensions of, say 6000 x 4000 pixels, it will look the same regardless of the resolution. However, where printing is concerned, a resolution of 300 dpi is necessary to give the best possible quality.
In Photoshop, here’s how images can be resized for screen display:
- Click Image Menu >>> Image Size. A dialogue will open.
- I recommend you use Pixels as the units of measurement.
- Make sure the Resample box is ticked.
- Although it will have no effect on file size, you may choose to set the resolution to 72 dpi. This will ensure that no-one is able to create a quality print from your images. If you change resolution, the pixel size will also change so make sure you set the resolution BEFORE changing the dimensions.
- Change the width to 1920 (or thereabouts) for landscape formats. The height will change automatically.
OR - Change the height to 1280 (or thereabouts) for portrait and square formats. The width will change automatically.
In summary:
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- editing and printing: don’t reduce the pixel dimensions or the resolution.
- screen display: reduce the pixel dimensions to not more than 1920 pixels horizontally and not more than 1280 pixels vertically. Optionally, set the resolution to 72dpi.
Save Images
This is a relatively straightforward process. I would recommend that you save your images either in jpg or psd (Photoshop format) files.
Jpg files contain far less information than RAW files or psd files so save as a jpg only if you are sure you have completely finished editing your image and it is in its final form. If you edit a saved jpg you will find that the quality will reduce every single time you resave. This is because jpg is a format which compresses an image and this is exponential with every save. With jpg files, whatever is visible on the screen at the time of saving will be saved as a single layer.
Save as a psd file if you think you will want to edit the image again at some point in the future. A psd file is a lossless format so there is no reduction in quality with each save. It will also preserve any layer structure in your image. Be aware that psd file sizes are much larger than jpg files. This not only requires more drive space but will also take longer to save and load.
In each case the method of saving is broadly similar:
- from the File menu click Save (or press CTRL S) or Save As (SHIFT CTRL S).
- If you have already saved the file, clicking Save will resave your file immediately in the same file format as the original file.
- If it is the first time you have saved or if you have clicked Save As, a file dialogue will open.
- Navigate to the folder where you want to save your file.
- Enter a name for your image.
- Choose a filetype from the dropdown menu headed ‘Save as Type:’.
- Click Save. If it is a psd file, it will be saved immediately. With jpgs, there is a further dialogue where you are asked to enter a value for Quality. This indicates the amount of compression which will be applied to the file. For screen, I set this at 7 and, for prints, 12 (ie no compression).
- Download this sample file.
- Open it in Photoshop.
- Experiment with different levels of magnification.
- Resize it to a suitable size for screen display.
- Save it as a jpg with a different filename.
