How do I scale down an image to a smaller size in GIMP without an unnecessary loss of resolution? I know that I am losing too much image resolution because when I downscale the same image using HTML code and display it in a web browser I am getting a noticeably sharper resolution. By noticeably sharper I mean that details that were completely absent in the downscaled image in GIMP are displayed the way they should be in the web browser, and the difference in resolution is easily visible without zooming in on the image.
I have already tried the answers to the following two questions, but none of the answers gave me the same image resolution that I am getting with my HTML code.
I am not looking for recommendations for web applications or services. I want to find a way to downscale images locally in my computer without an unnecessary loss of resolution.
This answer was suggested by Paolo Gibellini in two comments. It's also possible to downscale an image without losing too much resolution in GIMP using a similar method, however I prefer to use Inkscape because it's a lot easier to do it with Inkscape.
The original image can be a file format like .png, .svg, .jpg, etc., preferably .png or .svg because Inkscape will save .jpg images as .png files.
Open the original image file in Inkscape. When you open the file, Inkscape will open a small window asking you to select either link or embed image. Click the radio button to select embed.
Select File -> Export Bitmap. This will open a little Export Bitmap window.
Under the Export area heading in the Export Bitmap window click the Page button.
Under the Bitmap size heading in the Export Bitmap window select new values for Width and Height to downscale the image.
Click the Browse button and browse to the folder in which the file will be saved.
Type a name for the exported file with a .png extension to save it as a .png file or with an .svg extension to save it as a .svg file, etc.
Click the Save button.
Click the Export button.
Scaling bitmaps is never without loss. Both upscaling, and downscaling will produce interpolation artifacts. This can be done much better with vector graphics. So if we can trace the bitmap we will get better results.
Scaling artifacts become even more obvious when done on an indexed image. We can not calculate interpolated colors on downscaling an indexed image.
To still be able to scale an indexed image we should therefore change the image mode to RGB before we scale it. Details on downscaling will then be much better preserved:
If we need an indexed image mode we can change it back after scaling.