Guide for Image Resizing
Guide to correctly setting image size in Adobe Photoshop:
*Note that the majority of materials digitized in the Digital Labs of the NYPL are done so between resolutions of 300ppi and 1200ppi (PPI - Pixels Per Inch, or more commonly referred to as DPI - Dots Per Inch). This resolution depends on the materials and the size of the originals.
*On the occasion that you receive a digital file that reads at a resolution of 72ppi, please use the step-by-step guide below to properly change the files resolution to 300ppi (without compromising the integrity of the original file or interpolating the file to become a larger file size):
Open the TIFF file in Adobe Photoshop.
Once the file is open, go to the menu bar on the top of the screen and under “Image”, scroll down and select “Image Size…”
Once the “Image Size” dialogue box opens, you’ll notice that under “Document Size,” the “Resolution” may be set to 72ppi (but the size of both the width and height might seem much larger the object’s actual size.) See example below:
At the bottom of the dialogue box, the “Constrain Proportions” and the “Resample Image” boxes are highlighted in blue and checked.
Uncheck ONLY the “Resample Image” box. See diagram below:
Once the “Resample Image” box is unchecked (as referenced in the example above), change the resolution to 300ppi.
Once this is done correctly, both the width and height of the document will have dropped down in size, but neither the “Pixel Dimensions” nor the files size in MB’s have changed. See example below:
Once the resolution is properly changed to 300dpi, resave the file to either your Desktop or destination of choice. You will be replacing or overwriting the previous file that you have downloaded.
These steps should resolve any confusion when seeing 72ppi and thinking a particular file isn’t at high resolution.