How to erase/filter orange background millimeter paper on drawing

[carolinef33825687]

Is it possible to filter or erase millimeter paper on technical drawing ? I tryed to use the Background eraser or the Magic eraser but without any satisfying result. I join the test image that I use.

 

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[PECourtejoie]

Bonjour, Caroline.

une facon serait de convertir le fond en calque (double-clic sur le calque de fond dans la palette des calques)

Créer un nouveau calque, le remplir de banc le passer en dessous  (CMD(Mac)/CTRL(PC)+clic sur le bouton +)

Le remplir de blanc (CMD(Mac)/CTRL(PC)+Supprimer.

Ensuite, clic droit sur le calque de fond converti, sélectionner options de mélange.

Mélanger si, sélectionner Rouge.

Dans ce calque, effectuer un alt+glisser sur le triangle de droite.

[Norman Sanders]

Unfortunately, the color and lightness of the grid varies across the sample to the degree the suggested Blend If method sacrifices very light portions of the pencil notes.

The sample above was the result this alternate option:

1. Make a copy of the Red channel and deposit it as a Layer in the Layers panel.
2. Use Curves to move the highlight end point an amount that does not destroy the light pencil notes on the far right and the words between the curves.
3. Duplicate the layer and set the Blending Mode to Multiply.
4. Repeat Step 3 four times to build density. (The pencil texture will be sacrificed in order to gain a stronger black and greater legibility.)
5. Cmd+Shift+Opt+E to make a composite black & white layers
6. Touch up any traces of the grid with a soft edged brush.  

[PECourtejoie]

Yes, I also tried with a similar method, and a steep S curve on the Red channel, but I had some remaining phantom squares...

Many methods to achieve a given goal in Ps!

[Chuck Uebele]

You can add a B&W adjustment layer set to luminosity mode, then bump up the reds and yellows to turn them white. It will cause some lines through the writing that you can carefully paint back in using a mask.