# Check Axis overlay slot costs before adding another label > Use the Axis overlay capability response to review slot capacity and the cost of text and image overlays. Do not assume that every visible label consumes exactly one slot. - Canonical URL: https://update.dsesecurity.com/updates/check-axis-overlay-slot-costs-before-adding-another-label/ - Publisher: Detection Systems & Engineering (DSE Security) - Author: DSE Security Editorial Team - Published: 2026-10-29T19:49:58+00:00 - Modified: 2026-10-29T19:50:08+00:00 - Last reviewed by DSE: 2026-10-29 - Resource type: Guide - DSE priority: Advisory - Topics: IT, Video Surveillance - Reading time: 3 minutes ## What you need to know Use the Axis overlay capability response to review slot capacity and the cost of text and image overlays. Do not assume that every visible label consumes exactly one slot. ## Potentially affected Axis products exposing the documented Overlay API interface; confirm actual device, hardware and software applicability before applying the proposed checks. ## DSE recommendation DSE recommends reviewing an overlay budget and ownership map before an application creates or removes overlays. ## Article Bottom line: Check the device’s overlay resource accounting before adding another label or image. Review the reported costs and existing overlay identities rather than treating the visible item count as a reliable slot budget. ## Source fact: documented behavior Axis’s [Overlay API](https://developer.axis.com/vapix/network-video/overlay-api/) provides getOverlayCapabilities for the total slot count and the slot cost of text and image overlays. Its response describes numAvailableSlots, slotsPerTextOverlay and slotsPerImageOverlay, alongside limits such as maximum text length and image dimensions. An overlay receives an identifier when created; overlays may also be modified by internal applications, including overlays outside the ordinary text and image classes. ## What the source does not establish Do not assume the capacity field is a live free-slot counter without confirming its device-specific meaning. Do not remove another application’s overlay to make room for a label. Choose currently supported text/image options for the exact device, and do not infer a privacy-mask or image-quality result from resource availability. ## Applicability questions - What capacity and per-type costs does this device return? - Which existing overlay IDs belong to the affected application? - What text length or image dimensions does the proposed item require? - Which other applications or views depend on the current overlay arrangement? ## DSE recommendation: controlled next steps The following steps are DSE recommendations based on the cited source. DSE recommends reviewing an overlay budget and ownership map before an application creates or removes overlays. - Retrieve the supported capability response and list the current overlays through the documented workflow. Record IDs, type and owning application where known. Keep the capacity values and item list separate, and ask the integration owner to explain how its resource budget is calculated. Mark an unknown owner as unresolved rather than treating the overlay as expendable. - Describe the proposed label or image using harmless content. Compare its type, text length and dimensions with the returned limits, and use the documented per-type slot cost in the planning record. Avoid assuming an image and a text label have identical resource costs. Do not prescribe a larger font or image based only on a preview from another model. - In an authorized pilot, add the approved item and retain its returned ID and operation outcome. Inspect the resulting overlays and affected views. Re-read the relevant configuration if another application changes an item during the exercise. On an unresolved resource error, preserve the existing arrangement and investigate capacity and ownership before deleting unrelated objects. ## Verification and evidence Retain the capability response, before-and-after inventory, proposed item details and its returned identifier. Keep permitted view observations separate from the resource-accounting worksheet. Have another reviewer trace any removal to an explicitly owned object rather than to its position in a displayed list. Use a proposed desk case with different reported text and image costs and require the reviewer to calculate the intended budget from those values. Label the numbers as fixtures unless actually returned by the test device. This article supplies no universal slot count, completed allocation test or permission to alter another application’s overlays. ## Official references - [Overlay API](https://developer.axis.com/vapix/network-video/overlay-api/) — Axis Communications; official VAPIX documentation. Source review completed October 29, 2026. Recheck the official documentation and the deployed device’s capabilities before changing production settings. ## Primary reference - Name: Axis Communications — Overlay API - Authority: Axis Communications - URL: https://developer.axis.com/vapix/network-video/overlay-api/ - Source publication date: Not stated by the source ## Citation and use Preferred citation: “Check Axis overlay slot costs before adding another label,” DSE Security, https://update.dsesecurity.com/updates/check-axis-overlay-slot-costs-before-adding-another-label/ Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/ Usage and citation policy: https://update.dsesecurity.com/usage/ Copyright © 2026 Detection Systems & Engineering. All rights reserved.