poor resolution - saving the file

Forum|Forum|3 years ago
March 26, 2022
5 replies
328 views

Hi! I have a problem saving the file.
The scan made in 1200 dpi in pdf format is slightly corrected in Photoshop: I crop, straighten, remove the moire effect and shadow on the document. After saving the file also in pdf format, the quality of the document drastically differs from the original image. I tried to save the file using different save settings, but did not get a satisfactory result. The initial document (before processing) weighs approx. 5-6 mb, while after processing, the file weighs over three times as much (and looks three times worse). During one of the attempts, I obtained a satisfactory result in pdf format, but the file weighed less than 250 mb and therefore I cannot use it at a later stage of work. In the png format, the effect is quite good, but it weighs about 20 mb - even with maximum compression - which I don't quite like.
I would also like to add that at a later stage of the work I would like to combine multiple scans in inDesign and I am afraid that I will encounter the same problem with the save. The size of one file is also important to me, because there are nearly 200 of them - after combining the entire document, it can weigh a lot.
I am asking for help and suggestions.

Windows

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Conrad_C

Inspiring

@Wojciech23764382tc3a wrote:

The scan made in 1200 dpi in pdf format...
I would also like to add that at a later stage of the work I would like to combine multiple scans in inDesign and I am afraid

If the original scan was saved as PDF, that might be contributing to the problem. PDF is a container format, and an image can be included in a PDF at various compression settings. If the original scan was saved into PDF with too much compression or downsampling, the quality might be too low. Below is an example of the kinds of options that can affect image quality when saved as part of a PDF file, although your scanning software might not have all of these options.

To avoid the possibility that the image might end up with lower resolution or lower Image Quality, when scanning images for InDesign, the recommended workflow is to have the scanning software save them as TIFF or PSD (Photoshop) format, to preserve the full original quality of the image.

T

Test Screen Name

Braniac

Here's a thought. Perhaps you. An post an original uncorrected scan as PDF. So others can see why you want 1200dpi, and try the same experiment. It might be something as "simple" as blurring the moiré, so please tell us how you remove the moiré too. You may be going from 8 colours to millions.

rayek.elfin

Braniac

Are these colour or black&white originals?

If colour, 1200ppi is probably too high (barring very specific use cases such as the one @J E L mentioned).

If black&white, 1200ppi is fine as long as the files are saved as 1bit, and placed in the InDesign layout as 1bit. The file size should be a couple of MB at most in that case.

Since you mention a PNG version is only 20mb, I suspect you are scanning black&white images?

J E L

Braniac

Hi @Wojciech23764382tc3a Can you first explain why you are scanning at 1200 dpi? High settings like that are typically used when you need to capture very fine or highly-detailed information from originals such as film negatives and slides.

Derek Cross

Braniac

Why a resolution of 1200PPI (not DPI) – what are the dimensions you'll want the image to print at?

If you're going to Place the images in an InDesign document why not use the native Photoshop format of PSD?

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