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What are the Halftone image type(continuous tone photograph containing no text) and Combination image format(image containing halftone, text, or art elements)? What is the difference between these and simple photos in png/jpg? And why is it preferred to save in TIF?

Thanks in advance!

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  • Hi. Your question doesn't really make sense. A halftone is not a continuous tone photograph. Halftones have nothing to do with image formats like jpg/png/tiff, or text. Have you tried looking up the meaning of the word, or perhaps check out the wikipedia page?
    – Billy Kerr
    Commented Jun 27 at 15:21
  • Thanks, of course, I tried to understand by myself before posting, but I still can't get the difference. I received a file with requirements for figures and it's confusing. Here's the text: Halftone image type (continuous tone photograph containing no text ) should have thepreferred file format TIFF, with color mode being RGB or Grayscale, in a resolution of 300 dpi, and Combination image type (image containing halftone , text or line art elements ) should have resolution of 500-900 dpi.
    – YHR
    Commented Jun 27 at 15:33
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    These aren't halftones. They are also not photographs. These are raster images (images made of pixels). The first image looks like it may be a 3D render. The last image could be vector or line art, but you've posted a raster version of it. There's no way to tell.
    – Billy Kerr
    Commented Jun 27 at 16:39
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    Is there a chance this question could be because of a language/translation issue? I had a look at your other question, and it's a bit odd. Usually in graphic design we speak of raster and vector images. Raster images are formats like TIFF, JPEG, PNG. Vector formats are things such as SVG, AI, EPS, PDF (although vector formats can also contain raster images too).
    – Billy Kerr
    Commented Jun 27 at 17:25
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    It may also be a combination of lay knowledge and odd turns of phrases used by the journal the images are to be submitted to. Commented Jun 27 at 18:12

1 Answer 1

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Halftone images are single-value, yes or no images mostly used when printing, so let me explain why.

When printing, let's say on a black and white laser printer, you do not have gray toner, light gray toner, or super light toner. You only have black toner.

Q: So how do you represent different tones of gray?

A: You put less toner.

Q: Now the question is, how do you put less? You do not have transparent toner so you can layer it or stuff like that.

A: You make small dots or big dots, so small dots, so when viewed on a distance they look lighter, and on bigger dots, when clamped together they look darker.

So a halftone image is a 1-bit image, composed of dots, bigger or smaller to simulate gradients.

Here are 3 images. On the first one a grayscale image. You can have different gray values on each pixel. The second one, when viewed on a Full HD monitor at full screen, and stepping back a bit you can see some gradients, but in reality the pixels are either black or white. That is a halftone image. Halftones can have different shapes than round dots, lines rectangles etc.

Halftone is mostly used on offset print. If you take a look at any magazine with a magnifying glass you can see the Halftone of the four CMYK colors.

enter image description here

You can also have small dots, distributed randomly, with more density in some regions than others. That is dithering (Third image), and it is the newer approach for Halftone mostly used on digital print.


What is the difference between these and simple photos in png/jpg?

A "simple photo" is normally a color photo, it can be a grayscale too for stylistic reasons.

PNG, JPG is a file format. It can have color images or grayscale images. PNG can have indexed palettes (8bit). JPG format can not directly have 1-bit images. PNG can not, but you could have a 256 palette and have only 2 colors defined, making them look like a 1-bit image.

On my posted image I cheated because the 3 images are cramped on a single 8-bit grayscale JPG file. So technically the two images, center and right are not 1 bit, only made to look like it for explanatory purposes.

And why is it preferred to save in TIF?

Tif can also store 1-bit images.

One reason 1-bit images are preferred to be saved in TIF is because the file format can have additional information like resolution.


Not asked.

I am assuming they are asking you for 1-bit images, is because they want the responsibility for how the images will look at the end to be yours.

If you simply send them a color image, when "automatically converted" they probably won't show the details you need.

Here is a simulation.

Your original image, what you think would be grayscale, how could it be printed in 1 ink or laser print.

enter image description here

My recommendation is that you hire a designer to make customized conversions to your images so your final product works.

For example, the graphs that need some differentiation could look like a big smudge, texts could not be readable, the reliance on colored differentiation will disappear, etc.

Here is a grayscale image but treated a bit differently than your image "just as" and two different algorithms simulating two different ways a print can be made from a printer.

enter image description here

Open the images in a new tab to see the dots.

https://www.pexels.com/photo/woman-in-black-turtleneck-sweater-with-blonde-hair-3828245/

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  • Thanks a lot for your time and valuable information!
    – YHR
    Commented Jun 27 at 21:50

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