Photos with white backgrounds

[MarieMeyer]

This might be more of a Photoshop question than an InDesign question. However, I want to ask here it, because I think I will get a reply from someone with more experience of print production.

I am preparing a document for CMYK. It has a number of photos with white backgrounds, placed as JPEGs. I want to ensure that the white of the photo = paper white. Is proper color management alone sufficient to make this happen? Or is it necessary to replace the white background of the photo with transparency in Photoshop?

[MW Design · Accepted solution]

Paper color in ID does not equate to transparency in an image.

If these images have a truly white background and are not on the top of anything that uses color, you are good to go. (White, except with special printing conditions and an actual white ink, does not print.)

If these images are sitting on anything that uses color other than white, then you would need to remove the white from any such image in PS and then import the PSD file to retain that transparency.

Mike

[Bill Silbert]

I agree with everything that Mike said above. I would just like to add that areas of solid color in Photoshop may look consistent to the eye but  different sections of those areas often will read with different CMYK breakdowns when sampled with the eyedropper. So I would say that to be really sure that your areas that are white appear so in the final printing I would make them transparent and save the files as .PSDs before importing them into InDesign.

[MarieMeyer]

Thanks. This is a catalog and there are hundreds of them, so I really want to use JPEGS to keep the size of the ID file to a manageable level.

[Jongware]

So you are embedding these images?

[MarieMeyer]

Linking

[rob day]

Thanks. This is a catalog and there are hundreds of them, so I really want to use JPEGS to keep the size of the ID file to a manageable level.

The format of the file you place doesn't affect the size of the InDesign document in any meaningful way. If you were to embed images saved with any format, the ID file size would grow relative to the embedded file sizes, which is  why it is usually better to link all placed assets.

The only upside to using the JPEG format would be some saved disk space for the originals, which given today's storage costs has little or no value. When you place an image of any format, InDesign uses the placed pixels as they are and with JPEG the original image compression artifacts will be included. When you export the page, a JPEG would either be recompressed (adding additional compression artifacts to the original artifacts) or, if you choose no compression you will get a larger PDF file size and in both case the original compression is irrelevant.

Also, with white backgrounds you have to watch out for JPEG artifacts creeping into white areas, which depending on the amount of compression could show up as random halftone dots on press. Bottom line is you should give up on JPEG.

Here you can see random compression artifacts in the white background around the rasterized text. In a typical image the artifacts are not noticeable, but with pure white backgrounds they might show.

[Jongware]

Two additional footnotes to this extensive advice

1. If your images are now, or have ever been in the past, JPEGs, then re-saving as a non-lossy format (TIFF, PSD) is totally useless. To the point of being counter to what you'd expect: the artifacts in the JPEG will be preserved, and that brings down the compression rate. If they were JPEGs to begin with, clean them up in Photoshop. (*)

2. Review your PDF Export settings. Some of the standard ones include ... JPEG compression for images! It goes without saying (well, I am saying it now) that if you count on the images being clean after exporting, you must select any other option than "Automatic/JPEG".

(*) The magic wand is your friend. I also find it helpful to add an Adjust brightness layer on top of everything, with the contrast and brightness cranked to the max. That way you will see almost every slightly-off pixel stand out, and you can use the eraser to kill it. When done, simply delete the adjustment layer again.

[Scott Falkner]

MarieMeyer  wrote

Thanks. This is a catalog and there are hundreds of them, so I really want to use JPEGS to keep the size of the ID file to a manageable level.

The InDesign file size will not be affected by the format of the placed images. Any image placed, InDesign will generate a low resolution (72 ppi) JPEG for viewing. This image is embedded in the InDEsign file and is what you will see for Typical Display.

[MarieMeyer]

"Paper color in ID does not equate to transparency in an image."

I have this idea that transparency in a PS equates to "truly white" in a JPEG and therefore paper color when a ID file is printed. Is that correct? How do you define "truly white" and check for it in a JPEG?

[MW Design]

I have this idea that transparency in a PS equates to "truly white" in a JPEG and therefore paper color when a ID file is printed. Is that correct?

Not really. White as a color in an image is opaque and will knockout any color below it. If there is no colored elements below it, there is nothing to knockout and therefore only seems to have transparency. It's easy to test. In a new document, draw a rectangle and color it magenta and then import one of these images and size it so part is on the colored rectangle and part of it is off the rectangle. Then export to PDF. The part of the image on top of the rectangle will knockout the magenta and the part of the image off the rectangle will appear to be the same as the background of the PDF, which when viewed in Acrobat is typically just "white."

How do you define "truly white" and check for it in a JPEG?

Open the image in Photoshop. Move the cursor over a white area. In an RGB image, the readout in the Info panel will be 255,255,255 in a truly white area. If there is a reading other than that, there is color in what appears white.

Mike

[Bill Silbert]

Are you starting from PSDs with transparency already in them? If that is so then there is no reason to make them JPEGs before importing into InDesign. In inDesign whether the graphic frames they appear in are filled with InDesign's paper color or left with no fill against a non-filled background the "white" areas will appear as the paper color when printed.

[Stephen_A_Marsh]

It of course depends on the catalogue and image, however for many catalogue “product shot” images that “have a white background” it can be better to have a minimum highlight dot of say 3-5% for any large white areas in the image, leaving 0% for “specular” whites, chrome reflections, light sources etc. This provides a natural “border” around the catalogue image, which is helpful if the layout has a grid type layout. The image does not “disappear” off into the page. However if there are frames/borders around the images, then they are obviously “self contained”.