How to reduce the file size of scans initiated from the printer?

Question

My HP Deskjet 3050A printer saves scanned files as HUGE .png images. I scanned one page and it saved it as a .png file over 30 MB in size when using 600 dpi. Where would I find the printer settings to change the size it saves files at?

300 dpi saves at around 12 MB, and although I'm not sure that seems to be an awful large file size for a single image to me.

(The default "Printer" options on the computer have no settings that relate to scanning).

Solution 1

You can change the DPI (dots per inch) of the scanner. It will reduce file size and scanning speed, but also quality. Its usually shown under the "Resolution" tag of most Deskjets under the HP Scan window

The usual range for scanning regular documents without loosing too much quality is 300 dpi to 600 dpi, 600 dpi being recommended if you might need to zoom-in later on some page.

As a side note, scanners (especially cheap consumer scanners) may claim xxx dpi but the scan quality at the claimed optical resolution may be lacking, as well as the results at the maximum interpolated resolution.

The PNG images can also be compressed with tools such as Irfranview (which is a great tool, by the way, to do massive cut&crop, compressing, mass editing images, etc.), or online via CompressPng to further reduce size if you wish to keep them in the png format.

Solution 2

The main way to reduce the size of scans is by changing the resolution. This can be done at the scanner, or in the scanning software.

To print an acceptable image it only needs to be about 300dpi (dots per inch) and even 200dpi is quite acceptable. Once you go below 150dpi you will start to notice the degradation. Commercial printers usually request images at 300dpi.

This means that, if an image is printed with a size of 2", the scanned image only needs to be 600 pixels. If the print is the same size as the original, you need to scan at 300dpi. If the print is half the size of the original, you can scan at 150dpi but, if you will print at twice the original size, the scan needs to be 600dpi.

You should almost never have to scan at the printer resolution. This is because the scanner can see 16 million (or more) colours in every pixel, but most printers can only print eight colurs: the cyan, magemta and yellow inks, mixes of them (red, green and blue) plus black and white. For any other colours, the printer will put dots of those 8 colours side by side, and the eye will integrate them into a shade.

If you are scanning to view the image on the screen you only need as many pixels as are visible on the screen. In other words, for most current screens 1920 x 1080 pixels. An image that is 10" long only needs to be scanned at 192dpi. When sending photos by email, I usually reduce their size to something like 1200x800 pixels. The person recieving the email will be able to see the photo in full quality, and my email program does not have to send so much data. ALso, many email systems limit the size of an email to 10MB, so an email with just a few full-size photos might be rejected. Reducing them avoids that.

I have only talked about colour images. However, if you are scanning text or line art, you can set the scanner to Black & White or Greyscale. AT the same resolution, black & white makes the file 8 times smaller, greyscale about 3 times.

Another thing you can do is to change the file format. JPEG (JPG) files are usually the smallest. However, the more compressed a JPEG file is, the more fine detail you lose. Most cameras and scanners default to producing JPEG files, without any noticeable loss of detail. However, high-end cameras let you save all the details in a RAW format. With scanners you can select TIFF (TIF) for that. Another option is BMP with compression, which gives some file size reduction without any loss of detail.

Comments

[Julie Pelletier]

What model is your DeskJet and do you initiate the scan from it or from the computer?

[fixer1234]

What is the computer's operating system?

[Guy]

Apologies about being super late to answering this, but computer access I had was limited for outside reasons). Computer OS: Windows 7. Deskjet Model: 3050A. The scan is initiated from the printer.

[Yorik]

The paragraph with "You should almost never have to scan at the printer resolution." is what one might call "Not Even Wrong." It is inaccurate and misleading in detail, and confuses resolution with gamut. However, you are correct about 150-200dpi and opting for grayscale as effective ways of reducing file size.

[hdhondt]

Most printers claim well over 300dpi resolution. Unless the scan will be enlarged, you do not need to scan at that resolution.

[Guy]

Oh I found the "HP Scan" program on my computer and it's the 600 dpi setting that saves it as 31+ MB. Is that normal? And as for compressing the file I'd rather not have to compress the file every time I scan.

[Admin]

Yes , Memory cost for an image is computed from the image size , say a 600 dpi scan of 8 x 10 inch , with the image being 24 bit RGB or 3 bytes for pixel , will give us a 82 MB . , if you care about storage you need to either Lower the DPI , or if you still need that quality for zooming(you need to manually see how much you need by trying different DPI's) or Re printing ( lower then 300 dpi you start loosing quality). OR use 7zip/Winrar to Compress the output at the end .

[Admin]

If you Have Acrobat Reader Pro you can Save the scans as Optimised PDF so you dont compress each time each file .

[Vomit IT - Chunky Mess Style]

So what exactly did you do again, and what is important with the link, just for source or is there something more within that link that should be referenced in case the link goes bad?

[Jorge Jaime]

I meant you could find a windows software similar to Mac Preview. When I had this problem in Windows I solved in Mac OS X.