Processing Old Half-Tone illustrations in modern photo editing software.
March 29, 2021 8:54 AM Subscribe
I am doing a project that involves scanning illustrated printed material from the late 19th and early 20th century. Most of the illustrations are half-tones. Moiré patterns are making processing these photos with my editing software difficult. I am using Photolab 4.
Is there a way that these illustrations can be stabilized before processing that would dampen the Moiré effect?
Response by poster: Monotones
These are scans of machinery brochures and the originals are of indifferent quality.
posted by Raybun at 9:59 AM on March 29, 2021
These are scans of machinery brochures and the originals are of indifferent quality.
posted by Raybun at 9:59 AM on March 29, 2021
Is the moire pattern already in the image as an artifact of scanning, or is it due to manipulation after?
If not from the scanner, before modifying I generally enlarge the halftone image at least 2x, gaussian blur it a bit, shrink it about halfway between the enlargement and original size, gaussian blur a bit, then reduce to the original size, and then sometimes do an unsharp mask to regain some edges.
If the files from the scanner have the moire pattern, see if the driver has a 'descreen' or 'moire reduction' setting, or increase the scan DPI until you get a couple pixels for each dot.
posted by AzraelBrown at 3:16 PM on March 29, 2021 [2 favorites]
If not from the scanner, before modifying I generally enlarge the halftone image at least 2x, gaussian blur it a bit, shrink it about halfway between the enlargement and original size, gaussian blur a bit, then reduce to the original size, and then sometimes do an unsharp mask to regain some edges.
If the files from the scanner have the moire pattern, see if the driver has a 'descreen' or 'moire reduction' setting, or increase the scan DPI until you get a couple pixels for each dot.
posted by AzraelBrown at 3:16 PM on March 29, 2021 [2 favorites]
Many (gawd, many) moons ago, we used to use a sheet of transparent plastic, on an angle, to reduce the moiré pattern in halftone scans, and then gaussian blur to reduce other artifacts. YMMV.
posted by liquado at 11:30 PM on March 30, 2021
posted by liquado at 11:30 PM on March 30, 2021
This thread is closed to new comments.
It may no longer be relevant, but aligning your output halftone screen angles with the screen angle of the original image should save some ugliness....or is that obsolete, with current prepress techniques?
posted by wenestvedt at 9:17 AM on March 29, 2021