Registration black

[Woodpig]

Hi,

I'm putting a barcode on the back of a book cover, and I need it to be registration black (CMYK - 0% CMY, 100% K!). Is it enough to add an adjustment layer (Black and white adjustment) and set all the vales to maximum negative (-200%)? Or is there a better way?

THanks!

Gareth.

[loukash]

4 hours ago, Woodpig said:

to add an adjustment layer

An adjustment layer will rasterize anything below.
I definitely wouldn't ever want that happen to a barcode.

[lacerto]

4 hours ago, Woodpig said:

I'm putting a barcode on the back of a book cover, and I need it to be registration black (CMYK - 0% CMY, 100% K!).

Please double-check this. Registration black means 100% each of the four process colors (and is available as a special color also within Affinity apps). Barcodes however are typically printed in K100 (and CMY 0) to avoid misaligned process colors and best possible reading.

[Woodpig]

54 minutes ago, lacerto said:

Please double-check this. Registration black means 100% each of the four process colors (and is available as a special color also within Affinity apps). Barcodes however are typically printed in K100 (and CMY 0) to avoid misaligned process colors and best possible reading.

Thanks. Yes, I've checked with the publisher, and you're right. It's not registration black, it's K100, CMY 0.  So what's the best way of achieving that? Via an adjustment layer?

[walt.farrell]

37 minutes ago, Woodpig said:

So what's the best way of achieving that? Via an adjustment layer?

You said you're adding a barcode. What kind of file is the barcode that you're adding?

[Woodpig]

3 minutes ago, walt.farrell said:

You said you're adding a barcode. What kind of file is the barcode that you're adding?

It's a PDF, so a mixture of fonts and raster images. The barcode is a raster image.

[lacerto]

1 hour ago, Woodpig said:

The barcode is a raster image.

If your document is in CMYK mode, and your barcode is an RGB, grayscale, indexed or monochrome image, you can apply it "K-Only" button available on the context toolbar to make the image be treated like K-only image when exported to PDF. But it is a good idea to select the image and check what its placed pixel density is (you can see it on the context toolbar, or in the Resource Manager as a "DPI" value). If it is too high (typically 475dpi or more), it usually gets downsampled when exported, which would cause a blurred image, and it that case you might want to either resize (resample) the barcode manually in e.g. Photo, using the "Nearest Neighbor" algorithm, to keep edges sharp; or apply Threshold and Channel Mixer adjustments in Publisher/Designer where you have the image placed, to block CMY channels (setting their output percentage to zero and leave black to 100%) and force K-only output:

Can you post the Publisher/Designer page containing the barcode? Or if it is an EAN-13 (ISBN) barcode or similar, it could also be reproduced easily as e.g. K-only EPS pr PDF version (as vector graphics) so that you do not need to worry about the resolution or apply any adjustments on the image to make it work as expected.

[Woodpig]

25 minutes ago, lacerto said:

If your document is in CMYK mode, and your barcode is an RGB, grayscale, indexed or monochrome image, you can apply it "K-Only" button available on the context toolbar to make the image be treated like K-only image when exported to PDF.

This is very useful - thank you! However, I can't see a "k-only" button - where would that be? I'm using Affinity Photo.

[lacerto]

4 hours ago, Woodpig said:

This is very useful - thank you! However, I can't see a "k-only" button - where would that be? I'm using Affinity Photo.

You need to have a layer of image type selected that has a raster type of content (e.g. a PNG/TIFF/JPG file) selected to be able to apply the "K-Only" attribute for the layer. It is basically a meta information tag that can be assigned to these kinds of layers only. It is perfectly possible to place external images within a Photo document and keep them as "image" layers, but if they are already rasterized and you aim to produce "K-Only" raster date from within an RGB document, you are out-of-luck.

If you can post (or send as a private message) your .aphoto file I can try to give further advises, but the production specs can be so varied that it is hard to give exact instructions without knowing the details. 

UPDATE: If you are on macOS, you can convert a pixel type of layer to an image layer by right clicking an image and then choosing the conversion command from within the context menu.

 

[lacerto]

15 hours ago, N.P.M. said:

Copy>paste special>png  or other bitmap format

Yes, that would indeed do pretty much the same! Though it was a lousy instruction in the first place since a rasterized barcode (a pixel layer thing) might be useless anyway compared to the original placed image which might have better resolution, so converting that to an image resource using the macOS command does not do anything more than using this trick.

[lacerto]

On 2/24/2023 at 10:45 AM, Woodpig said:

I'm putting a barcode on the back of a book cover, and I need it to be registration black (CMYK - 0% CMY, 100% K!). Is it enough to add an adjustment layer (Black and white adjustment) and set all the vales to maximum negative (-200%)? Or is there a better way?

Here is a Photo document that has high-resolution barcode in bitmap format placed in the document (as image, so that it can be exported using higher PPI than what the document uses, in this case 300dpi, while the placed barcode uses 969dpi).

bitmapbarcode_prevent_downsampling.afphoto

bitmapbarcode_prevent_downsampling.pdf

The problem could be resolved easily simply by unchecking the Downsample option in PDF export settings, since in a single-page document that would not result in bloated file-size (over-sized placed images could well be rasterized on canvas, too). But this is a useful trick in multipage documents where one cannot afford turning off downsampling universally. It basically mimics using monochrome bitmaps (for which there is no support within Affinity apps):

Thresholding (typically at 50%) the RGB image (not one that is made "Black-only") and then blocking C, M and Y channels by using the Channel Mixer Adjustment results in K-only unblurred PDF output. Simply just outputting downsampled (K-Only made) barcode would result in fattened barcodes (and also nearly unrecognizable human readable numbers): I tested reading it with my mobile phone and got incorrect reading.

As mentioned, bitmap barcodes that do not need to be downsampled (that are prepared to the intended final size and resolution) only need to be made "K-Only" to be perfectly useable, so there is zero need to go for vector just for the sake of a "principle". But care must be taken with the resolution. (Vector images, on the other hand, might need care to avoid rasterization of fonts -- some barcodes are fully or partially generated using a font -- and K-only colors becoming converted to four-color blacks.)

[Woodpig]

Thanks very much, Lacerto. That's extremely useful. I'll digest your advice and get back if there are any issues.

Best wishes,

Gareth.